Seiko Mod Glossary: 750+ Terms for SKX, 5KX & NH35 Modding

750 Essential Terms From Horology Beats Glossary

This A-Z glossary covers the essentials for cases, movements, complications, tools, finishes, homages, and techniques—everything from Acrylic Crystal to Zulu Strap.

120-Click Bezel

A unidirectional rotating bezel with 120 detents or clicks. For reference, examples of our 120-click bezels can be viewed in the dedicated 120-click bezel collection.

12-Hour Bezel

A bi-directional rotating bezel with a 12-hour scale, allowing for tracking a second time zone or measuring elapsed time up to 12 hours.

150-Click Bezel

A unidirectional rotating bezel featuring 150 detents (clicks) for ultra-precise increments of 24 seconds over 60 minutes.

16mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 16mm wide. This size is common in smaller watches (34–38mm cases).

18mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 18mm wide. This size is typical for mid-size watches (36–40mm cases).

19mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 19mm wide. This uncommon size is typically found on watches with cases between 38–40mm, offering limited strap options.

20mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 20mm wide. This is the most common size for watches with cases ranging from 38–42mm. For more information, explore our wide range of 20mm watch cases. 

21mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 21mm wide. A custom strap is required for this size.

22mm Lug Width

The distance between the inner faces of the lugs for strap or bracelet attachment is 22mm wide. This width is standard for larger diving and tool watches with cases ranging from 40–46mm. We stock a range of 22mm lug SKX conversion cases.

24-Hour Bezel

A bi-directional rotating bezel with a 24-hour scale, designed for tracking a second or third time zone or for military time. It features 60 or 120 clicks and can be made of aluminium or ceramic. Often paired with a GMT hand, it typically has an arrow or pip marking at the 12 o'clock position. Explore our range of GMT and worldtimer bezel inserts

24-Hour Dial

A dial that includes 24-hour markings (1–24) instead of the traditional 12-hour format, used for military time or GMT displays. It may have an inner or outer chapter ring and is compatible with the NH34 movement.

24-Hour Subdial

A small auxiliary dial displays a 24-hour cycle (1–24 or AM/PM), typically positioned at 9 o’clock. The diameter ranges from 6 to 8 mm and is driven by the GMT complication. The numerals can be applied or printed, with optional luminescence.

28,800 VPH

Refers to the number of vibrations per hour of the balance wheel, translating to 8 beats per second (4 Hz). This is a standard high-beat frequency that provides a smoother seconds sweep. The amplitude target is set between 270° and 310°.

3-6-9 Dial

This dial layout features indices only at 3, 6, and 9 o’clock, excluding the 12 o’clock position; it offers a minimalist design inspired by Rolex. A 12 o’clock triangle or marker can be included for a clean, Explorer-style aesthetic.

3-Hand Date

This analogue display showcases hour, minute, and second hands, along with a date window located at 3 o’clock. The hands are centre-driven, conforming to NH35 standards. A date magnifier is optional. The dial has a diameter of 28.5 mm and allows for quick date adjustment via crown position 2.

316L Stainless Steel

This low-carbon austenitic alloy contains 16–18% chromium, 10–14% nickel, and 2–3% molybdenum. It is known for its corrosion resistance and non-magnetic properties, with a water resistance rating of over 200 meters. The hardness ranges from 150 to 200 HV, and it can have either a polished or brushed finish, serving as the standard for watch cases and bracelets. It is also hypoallergenic.

316L Bezel

The bezel, which can be rotating or fixed, is made from 316L stainless steel and can have a brushed or polished finish. It features a 120-click unidirectional option and is corrosion-resistant. The insert can be ceramic or aluminium.

36,000 VPH

Indicates the vibrations per hour of the balance wheel, which equates to 10 beats per second (5 Hz). This high-beat frequency allows for an ultra-smooth seconds sweep. The amplitude target is between 250° and 300°.

4 Lug Case

This watch case design includes four lugs (two on each side) for attaching a strap or bracelet. It is a standard configuration, with a lug width of 18–22 mm. Lugs can be drilled or solid, made from 316L or 904L steel, and are designed to accommodate spring bar mounting, resembling SKX/62MAS styles.

4R15 Movement

An entry-level automatic calibre from Seiko's 4R family, based on the 7S26 but featuring an upgraded Spron 510 mainspring for a power reserve of approximately 40-50 hours. It has a frequency of 21,600 bph (6 beats per second), 22 jewels, and measures 27.4 mm in diameter and 5.32 mm in height. This movement does not support hacking or hand-winding and has an accuracy of 35/+45 seconds per day. It includes a date complication only.

4R34 Movement

An entry-level automatic GMT calibre from Seiko's 4R family. Like the 4R15, it operates at 21,600 bph (6 beats per second) and has 24 jewels, measuring 27.4 mm in diameter and 5.32 mm in height. It provides a power reserve of around 41 hours, supports hacking and hand-winding (in a clockwise direction), and has an accuracy of 35/+45 seconds per day. The date is located at 3 o'clock, with an independent 24-hour hand. Learn everything you need to know by exploring the NH34 technical specifications.

4R35 Movement

This mid-range automatic calibre from Seiko's 4R family operates at 21,600 bph (6 beats per second) and has 23 jewels, with dimensions of 27.4 mm in diameter and 5.32 mm in height. It boasts a power reserve of around 41 hours, as well as hacking seconds and manual winding capability. The accuracy is rated at 35/+45 seconds per day, which can be tuned to ±15 seconds. The date position is at 3 o’clock, featuring a quick-set function. Find out more about the NH35 technical specifications

4R36 Movement

Another mid-range automatic calibre from Seiko's 4R family, this movement operates at 21,600 bph (6 beats per second) and uses 24 jewels, measuring 27.4 mm in diameter and 5.32 mm in height. It also has a power reserve of approximately 41 hours, supports hacking seconds and manual winding, and has similar accuracy as the 4R35, at -35/+45 seconds per day (tunable to ±15 seconds). It features a day-date complication located at 3 o’clock, which can be quickly set and is bilingual. You can find more information on this movement by diving deeper into the NH36 technical specifications.

40mm Case

The watch case has a diameter of 40mm, excluding the crown. This measurement falls within the common mid-size range of 38-42mm. The lug-to-lug distance is between 46-48mm, and the thickness measures between 11-13.5mm. The case is made of 316L or 904L stainless steel and typically features a water resistance (WR) of 200m. This size fits wrists ranging from 6.5 to 8 inches and follows the style of the SKX007 and 62MAS.

42mm Case

The watch case has a diameter of 42mm, excluding the crown, categorising it as a larger mid-size watch within the 40-44mm range. The lug-to-lug distance varies from 48-50mm, and the thickness is between 12-14mm. Made from 316L or 904L stainless steel, this case can achieve a water resistance of over 200m. It is suitable for wrists measuring 7 to 8.5 inches, aligning with modern diver/tool watch standards.

45mm Case

The watch case has a diameter of 45mm, excluding the crown, which categorises it as a large size within the 44-48mm range. The lug-to-lug measurement is between 50-54mm, and the thickness is between 13-15mm. Made from 316L or 904L stainless steel, this case is capable of over 200m water resistance and is designed to fit wrists measuring 7.5 to 9 inches, often reflecting the Panerai/tool watch style.

4R56 Movement

The 4R56 is a mid-range automatic movement from Seiko’s 4R family. It operates at 21,600 beats per hour (6 beats/sec) and contains 24 jewels. The movement has a diameter of 27.4mm and a height of 5.32mm, with an approximate power reserve of 41 hours. It features hacking seconds and can be manually wound in a clockwise direction. This movement's accuracy ranges from -35 to +45 seconds per day (tunable to ±15). It includes a day-date function at the 3 o’clock position, with quick-setting and bilingual options. The 4R56 is found in vintage-style Seiko 5 Sports and Prospex models and is known as NH56 when outsourced.

5 Sports Mod

This custom watch build utilises the Seiko 5 Sports base (SRPD/SRPX series) as a donor for the case, movement (4R35/4R36/NH35/NH36), and hands. It serves as an affordable entry-level platform for beginners, with a 40mm case, 20mm lugs, and 200m water resistance. The mod is compatible with SKX parts (bezel, inserts, crystals), making it a gateway to the modding hobby.

5KX Series

The Seiko 5 Sports SRPD/SRPX lineup (2019–present) is the successor to the discontinued SKX007/009 divers. It features a 42.5mm 316L case, 46mm lug-to-lug, and a thickness of 13.4mm, along with a 100m WR. The watch is equipped with a Hardlex crystal and either a 4R36 or NH36 movement (41-hour power reserve, hacking, and hand-winding). Visit Seiko to view the latest 5KX series 

6R15 Movement

The 6R15 is a mid-range automatic movement from Seiko’s 6R family. Operating at 21,600 beats per hour (6 beats/sec) and containing 23 jewels, it has a diameter of 27.4mm and a height of 5.32mm. The movement provides a power reserve of approximately 50 hours and features hacking seconds and manual winding. Its accuracy is rated between -15 and +25 seconds per day, with a date function at the 3 o’clock position and quick-setting capability. This movement is commonly used in the Seiko Prospex “Sumo” models (SBDC001/031).

6R35 Movement

The 6R35 movement is another mid-range automatic calibre from Seiko’s 6R family. It operates at 21,600 beats per hour (6 beats/sec), contains 24 jewels, and features a diameter of 27.4mm with a height of 5.32mm. It boasts a 70-hour power reserve, hacking seconds, and manual winding, with an accuracy of -15 to +25 seconds per day. The date is located at the 3 o’clock position and is quick-set. This movement is featured in Seiko Prospex models like the “SPB” Turtle and Alpinist, offering an extended power upgrade over the 6R15.

6R64 Movement

The 6R64 is an automatic GMT watch movement produced by Seiko Instruments Inc., released in 2018. It includes a GMT (dual time zone) hand, a power reserve indicator, and a pointer-style date at the 6 o’clock position instead of a traditional date window. The movement features a 45-hour power reserve, operates at a frequency of 28,800 vibrations per hour (8 beats per second), and utilises 29 jewels.

6R64 Chrono

The Seiko Calibre 6R64 is an in-house automatic (self-winding) mechanical watch movement with GMT functionality (dual time display). It includes a date sub-dial and a power reserve indicator. Known as a "traveller's" GMT, the main hour hand can be adjusted independently in one-hour increments, which is ideal for quickly changing time zones without disrupting the minutes and seconds hands.

7S26 Movement

The 7S26 is an entry-level automatic calibre from Seiko, produced from 1996 to 2019. It operates at 21,600 beats per hour (6 beats/sec), contains 21 jewels, and features a diameter of 27.4mm with a height of 4.8mm. This movement offers an approximate 40-hour power reserve but lacks hacking or hand-winding capabilities. Its accuracy ranges from -20 to +40 seconds per day and can provide either a date or day-date function (7S26A/B/C). It is equipped with Diashock protection and was used in the SKX007/009 divers and the Seiko 5. The 7S26 was later replaced by the 4R35/4R36 movements.

7S26 Stem

The 7S26 stem is the winding stem rod (part number 351.260) designed specifically for the Seiko 7S26 automatic watch movement. Its primary function is to act as the external connection point for users to interact with the watch's internal mechanisms via the crown.

7S36 Movement

The 7S36 is an entry-level automatic calibre from Seiko, produced from 1996 to 2019. It operates at 21,600 beats per hour (6 beats/sec), contains 23 jewels, and features a diameter of 27.4mm with a height of 4.8mm. Like the 7S26, it offers an approximate 40-hour power reserve but does allow for manual winding (unlike the 7S26) while still lacking hacking capabilities. Its accuracy also ranges from -20 to +40 seconds per day, and it includes a day-date function at the 3 o’clock position, presented bilingually. This movement features Diashock protection and was utilised in the Seiko 5 SNK/SNZ series, serving as a predecessor to the NH36.

904L Steel

904L is a high-grade austenitic stainless steel alloy composed of 20% chromium, 25% nickel, 4.5% molybdenum, and 1.5% copper. It offers superior corrosion and pitting resistance compared to 316L steel. Its hardness ranges from 150 to 200 HV, and its polished finish retains its lustre. Non-magnetic and capable of providing over 300m of water resistance, 904L is considered a premium material for watch modifications and is the standard used by Rolex.

A. Lange Homage

This custom Seiko modification is inspired by A. Lange & Söhne's elegant German watchmaking. It features a 38mm case with a guilloché dial texture, a railway minute track, and slim dauphine hands. The watch is powered by an NH35 movement and protected by a sapphire crystal, making it a rare luxury homage build.

Accuracy Tuning

Accuracy refers to how closely a watch keeps time compared to the true time. Several factors influence a watch's accuracy, including the type of movement, environmental conditions, and regular maintenance.

Acrylic Crystal

The lightweight, shatter-resistant lens made from PMMA (polymethyl methacrylate), also known as Plexiglas or Hesalite, is used instead of glass. This material was commonly utilised in the 1960s and 70s by divers (the predecessors to the SKX).

Acrylic Insert

In watch terminology, an acrylic insert typically refers to the watch crystal—the transparent cover over the dial—made from PMMA, also known by trade names like Plexiglass or Hesalite.

Adjustment Lever

A small, movable lever used to regulate the watch's timekeeping mechanism, allowing it to run slightly faster or slower.

Aging Solution

The term "ageing solution" can refer to two concepts: the natural process by which a watch deteriorates over time, resulting in a unique "patina" or character, or a method used to artificially and rapidly age a watch to give it a vintage appearance.

Alu

This is an abbreviation for aluminium, referring to lightweight, anodised aluminium bezel inserts (38.5mm outer diameter, 1.2mm thick) used in divers to achieve a vintage aesthetic.

Aluminum Bezel

The aluminium bezel is a metal ring that surrounds the face of a watch or a device’s screen. It holds the crystal or glass in place and provides both a functional and decorative frame. In watches, aluminium is a lightweight and relatively inexpensive material that is often anodised for various colours, although it tends to scratch more easily and fade over time compared to more modern materials like ceramic.

Aluminum Insert

An aluminium insert is a lightweight, cost-effective ring that fits into the bezel, which is the metal ring surrounding the watch's crystal. This insert typically displays time-related markings and is appreciated for its vintage aesthetic, light weight, and ability to develop a unique patina over time due to scratching.

Amethyst Crystal

In watches, "amethyst crystal" refers to a component made from natural amethyst, a violet variety of quartz, which may be used for the dial or other elements.

Amplitude

Amplitude is the measurement of the degree of rotation of the balance wheel, expressed in degrees, from one extreme to the opposite in its swing.

Analog Display

An analogue display is a traditional method of showing time on a watch using rotating hands (hour, minute, and second) that point to markers or numbers on a circular dial.

Anchor Escapement

The anchor escapement is a mechanical mechanism in watches responsible for regulating the release of energy from the mainspring to the balance wheel, thus controlling the movement of the watch's hands.

Anglage

Anglage is a watchmaking finishing technique where the sharp, right-angled edges of movement components are filed at a 45-degree angle and polished to create a bevelled, or chamfered, edge.

Anodized Bezel

An anodised bezel refers to the outer ring that frames the watch face and is made of anodised aluminium. The anodising process creates a protective, durable, and often colourful coating that is lightweight and affordable, though it may be prone to scratching and fading over time.

Anti-Backlash Gear

An anti-backlash gear is designed to minimise or eliminate the small, inherent gap (backlash) that occurs between meshing teeth.

Anti-Corrosion

Anti-corrosion refers to the capability of a watch's materials and construction to resist degradation from environmental factors such as sweat, moisture, and saltwater.

Anti-Fingerprint

Anti-fingerprint refers to a coating or screen protector that resists and minimises the visibility of fingerprints, oil smudges, and dirt on the watch face or case.

Anti-Magnetic

An anti-magnetic watch is designed to resist the effects of magnetic fields, which can cause a conventional mechanical watch to become magnetised and keep inaccurate time.

Anti-Reflective Coating

This is a thin, specialised layer applied to the watch crystal to minimise light reflection and reduce glare, making the watch face easier to read.

Anti-Shock

A watch is considered shock-resistant if it can withstand shocks to the movement, particularly to the delicate pivots that support the balance wheel. Various brands use different methods to achieve this, generally involving a spring suspension system for the balance wheel.

Anti-Static Brush

An anti-static brush is a specialised tool with conductive bristles—often a mixture of natural and synthetic fibres—used to safely remove dust and debris from delicate watch parts without generating damaging electrostatic discharge (ESD).

Anti-Static Gloves

Anti-static gloves are specialised gloves designed to prevent electrostatic discharge (ESD) in the context of watch maintenance and repair.

Anti-Tarnish Paper

Anti-tarnish paper is a special, acid-free paper used to protect the metal components of watches from tarnishing.

Applied Chapter Ring

An applied chapter ring is a feature on a watch dial where a separate, raised ring is affixed to the surface, typically marked for minutes or seconds, enhancing legibility and adding depth.

Applied Gold Indices

These are three-dimensional hour markers on a watch dial made of gold and physically attached to the dial.

Applied Indices

Similar to gold indices, these are three-dimensional hour markers that are physically attached to the watch dial.

Applied Lume

This method involves applying luminescent paint to watch components, such as hands and hour markers.

Aquanaut Homage

This type of watch is produced by a brand other than Patek Philippe but is heavily inspired by the design of the original, high-end Patek Philippe Aquanaut watch.

Arabic Dial

A characteristic of Eastern Arabic numerals (٠, ١, ٢, ٣) is found on some luxury models designed for the Middle East.

AR Blue Coating

This type of anti-reflective (AR) coating is specifically tinted blue due to the manufacturing process and is often combined with a blue light-filtering feature.

AR Green Coating

Similar to the blue coating, AR green coating has a green tint resulting from its manufacturing process and is often combined with a green light-filtering feature.

AR Neutral

"AR neutral" describes an anti-reflective coating that does not have a noticeable colour tint, typically appearing nearly invisible or clear.

AR Sapphire

This refers to sapphire glass with an anti-reflective coating applied to its surface, reducing glare and enhancing light transmission. Explore our stock of AR sapphire crystal

Assembly Lubricant

Using lubricant during the assembly and servicing of a watch movement is essential to reduce friction between moving parts and limit wear on contact surfaces.

Auto Rotor

An auto rotor is a semi-circular, weighted component in an automatic watch that pivots freely with the motion of the wearer's wrist.

Automatic Movement

An automatic movement is a self-winding mechanical watch mechanism that uses the wearer's natural wrist and arm movements to keep the watch running without requiring manual winding or a battery.

Automatic Winding

This mechanism allows the watch to automatically wind the mainspring, using the wearer's natural wrist movements to store energy and power the watch.

Auxiliary Dial

An auxiliary dial is a smaller dial on a watch's main face that displays information beyond just the basic time. These dials are often used for various complications, such as tracking elapsed seconds, minutes, and hours in a chronograph function.

Azurage

Azurage is a decorative finish that creates a rippling, wave-like effect with overlapping concentric circles, typically applied to sub-dials or the main dial of a watch.

Balance Bridge

A component in a watch's mechanical movement that secures the top pivot of the balance wheel.

Balance Cap

In a mechanical watch, the balance cap (or cap jewel, also known as an end stone) is an unpierced, flat-bottomed synthetic jewel typically made of ruby or sapphire.

Balance Jewels

Balance jewels are synthetic ruby or sapphire bearings that reduce friction at the most critical points of a mechanical watch's balance wheel assembly.

Balance Wheel

The balance wheel is the timekeeping component of a mechanical watch that oscillates back and forth, functioning like a pendulum to regulate the release of energy from the mainspring.

Ball Bearing Rotor

A semicircular weight that swings with the wearer's motion to automatically wind the mainspring. It employs a set of ball bearings to reduce friction and ensure smooth, reliable rotation.

Bar

A bar is a unit of measurement for a watch's water resistance, indicating the static pressure it can withstand, with 1 bar being roughly equivalent to the air pressure at sea level.

Barrel

A cylindrical metal drum that houses the mainspring, which stores and releases energy to power a mechanical watch.

Barrel Arbor

A barrel arbor is the central shaft of a mechanical watch's mainspring barrel, around which the mainspring is wound.

Barrel Cover

A barrel cover, or barrel cap, is a specific component of the mainspring barrel, responsible for storing and releasing the power that runs the watch.

Barrel Gasket

A barrel gasket is a small, typically round, flexible seal (usually made of rubber or silicone) used for waterproofing a component known as a barrel.

Base Dial

The "base dial" of a watch is the primary surface or disk that serves as the foundation for all other watch face components, such as the hands, hour markers, and brand logos.

Base Gasket

The term "base gasket" typically refers to the case back gasket, a crucial component that ensures the watch's water resistance and protects its internal mechanisms.

Base Model

A "base model" is the simplest, most fundamental, and often most affordable version within a specific product line or a brand's catalogue. A stock Seiko donor, such as the SKX007, is a great starting point for modifications.

Base Washer

In watchmaking, "base washer" is not a widely recognised technical term. The likely component being referred to is a dial washer, a small, often slightly curved washer used in the watch movement, such as those found in models like the 4R34 or NH34.

Baton Hands

Baton hands-on watches are long, straight, and rectangular, characterised by their simple and minimalist design. View our stock of baton handsets.

Bead Blast

Bead blasting creates a matte, non-reflective finish on watches by blasting the surface with high-pressure glass beads. This technique is ideal for achieving a military or tactical look, hiding minor scratches and fingerprints, and reducing glare. Explore our range of bead blasted, matte SKX conversion cases.

Bezel Gasket

A bezel gasket is a small, flexible seal, typically made of rubber or silicone, that fits between the bezel and the case of a device, most commonly a watch.

Bezel Lock

A bezel lock is a mechanism designed to secure a rotating bezel, preventing it from turning accidentally. It is most commonly found on diving watches.

Bezel Opener

A bezel opener is a specialised tool used primarily in watchmaking and jewellery making to safely remove the bezel, the ring surrounding the watch face or a gemstone setting from the main body or case.

Bezel Screw

A bezel screw is a functional or decorative threaded fastener used to secure a bezel to the main assembly.

Bi-Color Bezel

A bi-colour bezel is a watch bezel that is divided into two distinct colours, most famously seen on GMT watches, to help distinguish between day and night hours.

Bi-Color Hands

In horology (watchmaking), "bi-colour hands" refers to watch hands that feature a design incorporating two distinct colours or materials, often for functional or aesthetic purposes.

Bi-Compax

A bi-compax watch is a chronograph featuring two sub-dials. This layout originally stemmed from a specific watch brand's "compax" naming convention, but is now commonly used to describe any chronograph with two registers.

Bi-Directional Bezel

A bi-directional bezel is a rotating ring on a watch that can turn both clockwise and counterclockwise. This feature allows for greater flexibility in timing and calculations, such as tracking elapsed time, setting different time zones on GMT watches, or performing calculations with a tachymeter bezel.

Bill of Materials (BOM)

A structured list of all components, parts, and materials needed for manufacturing, including raw materials and subassembly parts.

Black Cerachrom

This is a specific, patented, high-performance black ceramic material developed and manufactured in-house by the luxury watchmaker Rolex for use in its watch bezels.

Black Ceramic

Black ceramic is a high-tech material utilised for components like cases and bezels. It is valued for its strength, scratch resistance, and sleek black colour, which is integral to the material itself and does not fade.

Black Dial

A black dial refers to a black watch face, a classic and versatile colour that conveys professionalism, power, and sophistication. The primary advantage of a black dial is its high legibility, providing strong contrast with bright or luminous hands and markers, making it easier to tell time. It is often favoured for stealth modifications.

Black IP Coating

Black IP (Ion Plating) coating is a durable, thin black finish created through a Physical Vapour Deposition (PVD) process. In this method, a metal is vaporised in a vacuum and then bonded to the watch's surface at a molecular level.

Black Polishing

This is a high-end watch finishing technique that creates a mirror-like surface on metal components, which appears deep black from certain angles.

Black PVD

Black PVD stands for Physical Vapour Deposition and is a process used to apply a hard, durable, and decorative black coating to the watch case and bracelet. During this high-tech vacuum process, a material is vaporised and bonded at an atomic level to the surface of the watch, creating a thin, resistant layer that is more durable against scratches, corrosion, and wear than traditional finishes.

Black Rhodium

Black rhodium is a mixture of rhodium and other metals and chemicals that produces a dark colour. This mixture is then used to plate other metals, such as sterling silver and gold.

Blue AR Coating

Blue AR (anti-reflective) coating is a layer applied to the watch crystal that reduces glare and improves legibility by allowing more light to pass through.

Blue AR Crystal

A watch crystal with an anti-reflective (AR) coating that appears blue at certain angles.

Blue Hands

"Blue hands" refer to watch hands that acquire their colour through a traditional heat-treating process, which oxidises the steel to create a deep, durable blue colour rather than using paint.

Blue Lume

Blue lume is a phosphorescent material applied to watch dials, hands, and indices that glows blue in the dark. It is often referred to as BGW9.

Blue Steel Hands

These refer to handmade steel hands that have been heat-treated to achieve a blue colour, a traditional process that serves both aesthetic and functional purposes.

Blued Screws

Blue screws are steel screws that have been thermally treated to achieve a distinct blue colour by heating them to a specific temperature.

BOM Checklist

In manufacturing, including watchmaking, a BOM checklist refers to a detailed, structured Bill of Materials (BOM) document that serves as a complete "recipe" or blueprint for creating the product.

Bombé Bezel

In watchmaking, a bombé bezel refers to a bezel with a distinctly rounded or convex (domed) profile. The term comes from the French word “bombé,” meaning “rounded” or “curved.”

Bombé Case

In horology, a bombé case refers to a watch case featuring lugs that are distinctly rounded, curved, or domed in shape. The term “bombé” derives from the French word meaning “bomb-shaped” or “domed.”

Bracelet Polish

Bracelet polishing is the process of removing scratches and imperfections from a watch bracelet to restore its shine and original appearance.

Brass Bezel

A bezel is the circular outer ring that frames the watch face. It can be either fixed or rotating and is typically made from materials such as stainless steel, ceramic, or precious metals. 

Brass Case

A brass case in a watch refers to the protective outer housing made from brass, a copper-zinc alloy. This material is known for its warm, golden appearance, which can give a watch a vintage look.

Brass Chapter Ring

A brass chapter ring is a separate, raised ring made of brass that sits between the dial and the crystal. It is often decorated with hour and minute markers and replaces the standard printed minute track on the dial. This feature provides a distinct look and may sometimes include luminous markers for visibility in low-light conditions. 

Brass Dial

The brass dial serves as the base material for a watch's face, displaying the time. Brass is a popular choice for this purpose due to its malleability, durability, corrosion resistance, and cost-effectiveness, making it easy to shape, engrave, and finish. 

Breathing Gasket

A breathing gasket is a porous seal designed for helium release, particularly used in saturation diving. 

Breguet Hands

Breguet hands are a distinctive style of watch hands, featuring a thin profile with a small hollow circle near the tip that resembles an apple. Named after their inventor, Abraham-Louis Breguet, these hands were originally designed for elegant simplicity and legibility.

Breguet Overcoil

A Breguet overcoil is a type of balance spring used in watches where the outermost coil is bent upwards and inwards, forming a "U" shape. This modification, invented by Abraham-Louis Breguet, allows the spring to expand and contract more concentrically and evenly.

Brushed Bezel Edge

A brushed bezel edge features a matte finish created by fine, parallel lines etched into the metal, giving it a non-reflective, satin appearance. 

Brushed Finish

A brushed finish on a watch is a surface treatment that uses a fine abrasive to create a series of parallel, hairline scratches. This results in a matte, non-reflective, and textured look. 

Build Checklist

A watch build checklist refers to either a list of all the necessary components for assembling a watch or a quality control checklist used to inspect a finished watch. 

Butterfly Clasp

A butterfly clasp is a type of watch clasp that has two hinged "wings" that fold out from the centre and close in opposite directions, resembling a butterfly's wings.

Butterfly Deployment

A butterfly deployment in watches is a type of secure folding clasp that features two hinged, wing-like pieces that fold out from the centre to open and snap shut to close.

C3 Green Glow

In watches, C3 refers to a specific type of Super-LumiNova known for its strong, bright green glow and long-lasting luminescence. It is recognised as the brightest colour of Super-LumiNova, appearing as a pale or yellow-green during the day and charging to a vivid green in the dark. 

C3 Super-LumiNova

C3 Super-LumiNova is a luminous paint used on watch hands and markers that provides a very bright and long-lasting green glow. 

C3 Vial

In the context of watches, a C3 vial refers to a specific type of Super-LumiNova, a high-performance phosphorescent material that enables watch hands and markers to glow in the dark. 

Calendar Complication

A calendar complication is any function on a watch that goes beyond simply telling the time and displays additional information, such as the date, day, or month. 

Calendar Jumper

In watches, a calendar jumper refers to a component within the date display mechanism, typically a flat spring that snaps a date wheel into a new position. More broadly, it relates to the “jump hour” complication, where the hour display jumps instantly to the next hour instead of moving gradually. 

Calendar Window

A calendar window on a watch is a small aperture on the dial that displays the current date (ranging from 1 to 31) and sometimes shows the day of the week or month. 

Cannon Friction

In watch modding, cannon friction refers to the friction generated by the cannon pinion on the movement's centre wheel arbor. This friction is essential for the proper setting and function of the watch hands. 

Cannon Pinion

The cannon pinion is a crucial component in a mechanical watch's movement that connects the gear train to the watch hands. It is a small, toothed tube fitted on the centre wheel's arbor and rotates with it, allowing the minute hand to be set manually while translating motion from the watch's gears to display the time on the dial. Its teeth drive the minute wheel, which subsequently drives the hour wheel. 

Cannon Tight

Cannon tight refers to the correct friction or tension of the cannon pinion. This component serves as the friction coupling that connects the movement's gears to the watch hands, allowing them to be set while also being driven by the movement. 

Canvas Buckle

A canvas buckle in the context of watches refers to the closure mechanism on a canvas watch strap. It can be a traditional tang buckle (similar to a belt buckle) or a more modern folding clasp that fastens the strap around the wrist. 

Canvas NATO

A canvas NATO watch strap is a type of one-piece strap, originally designed for military use, made from tightly woven cotton fabric instead of nylon.

Canvas Strap

A canvas strap for a watch is a band made from durable, tightly woven fabric, typically cotton, that attaches the watch to the wrist. 

Carbon Bezel

A carbon bezel in a watch is crafted from a composite material called carbon fiber, known for its high strength-to-weight ratio, durability, and distinct aesthetic. This material is often used as an alternative to traditional materials like steel, resulting in a lighter, more modern, and resilient watch component.

Carbon Dial

A carbon dial on a watch refers to a watch face made from a carbon fibre composite. This material is known for being lightweight, strong, and durable. It often has a distinctive marbled or "forged" appearance due to the compression of the carbon fibres under pressure.

Carbon Fibre Dial

A carbon fibre dial in a watch is a watch face crafted from carbon fibre, a material renowned for its exceptional strength, lightweight nature, and resistance to scratches and corrosion.

Case Back

The case back of a watch is the rear cover that seals the watch case, protecting the internal movement from dust, moisture, and damage.

Case Back Engraving

Case back engraving in watches refers to the process of etching text or images onto the metal back of the watch case.

Case Back Gasket

A watch's case back gasket is a thin rubber or silicone O-ring that creates a watertight and dust-tight seal between the case and the watch's back cover.

Case Back Wrench

A case back wrench is a tool used in watchmaking to open the screw-on back cover, or case back, of a watch.

Case Bead Blast

In watchmaking, bead blasting is a surface finishing process that results in a matte, non-reflective, and uniform appearance on a watch case.

Case Finishing

Case finishing is the process of manipulating the surface of a watch case to achieve a specific texture and appearance, influencing both its aesthetics and tactile feel.

Case Gasket

A case gasket in a watch is a seal, typically made from rubber or silicone, which creates a watertight barrier between the components of the watch case.

Case Gasket Kit

A watch case gasket kit contains various rubber or silicone sealing rings used to maintain a watch's water resistance and protect its internal components from moisture, dust, and dirt.

Case Height

Case height is the vertical thickness of a watch, measured from the bottom of the case back to the top of the crystal.

Case Horns

In watchmaking, case horns, also known as lugs, are the four extensions of the watch case that attach to the watch strap or bracelet.

Case Lug Width

Case lug width refers to the distance between the two lugs on a watch case where the strap or bracelet attaches. It is measured in millimetres and is crucial for purchasing a new strap, as a replacement must match the lug width to fit correctly.

Case Material

The case material is the external shell that protects the internal components, such as the movement, dial, and hands. The material significantly affects the watch's durability, water resistance, weight, and overall aesthetics. Common options include stainless steel, titanium, gold, and ceramic.

Case Polishing

Case polishing is a skilled process that removes surface imperfections like scratches and scuffs from the watch case and bracelet, restoring a smooth and high-shine finish.

Case Pressure Test

A case pressure test is a method used to verify a watch's water resistance by subjecting it to air pressure to check for leaks in its seals and gaskets.

Ceramic Bezel

A ceramic bezel is the outer ring surrounding a watch's dial, made from a durable, scratch-resistant high-tech ceramic material. It enhances the watch's appearance and provides longevity due to its resistance to scratches, corrosion, and fading.

Ceramic Coating

Ceramic coating refers to an extremely hard, scratch-resistant, and corrosion-proof material, such as zirconium oxide, which may be used to coat a watch's parts or serve as the primary material for components like the case, bezel, or bracelet.

Chapter Ring

A watch's chapter ring is mounted on the outer edge of the dial and displays time-related markings, such as minute or second tracks. It can be located directly on the edge of the dial or on the "rehaut," a raised inner bezel.

Chrono Bezel

A chrono bezel is a specific type of bezel found on chronograph watches. It is a fixed or stationary ring around the crystal that is used for calculations, most commonly featuring a tachymeter scale to measure speed.

Chrono Hand

A chrono hand is the stopwatch hand on a chronograph watch, which is a type of watch that includes a built-in stopwatch function.

Chrono Pusher

A chrono pusher is a small button located on the side of a watch, used to control the chronograph or stopwatch function.

Chronograph

A chronograph in a watch is a complication that functions as a stopwatch, enabling the measurement of elapsed time in addition to displaying the regular time.

Click Ball

A click ball is a small metal ball, often on a spring, used in certain types of rotating bezels to create a distinct and solid "click" sound and feel.

Click Spring

A click spring in a watch bezel is a shaped, spring-loaded component located between the watch case and the bezel. Its prongs or raised sections engage with notches on the underside of the bezel as it rotates, creating the distinct "click" sound and providing a precise ratcheting motion that prevents accidental movement.

Click Spring Steel

A click spring is a small, stamped steel component in a watch bezel that produces the tactile "click" sound and feel when the bezel is rotated, ensuring precise and secure positioning.

Click Weight

This refers to the tactile feedback strength provided by the click spring.

Clous de Paris

Clous de Paris is a decorative pattern consisting of small, raised pyramid shapes, also known as a hobnail pattern, created through a technique called engine-turning or guilloché.

Clutch Lever

A watch's clutch lever, often referred to as a yoke, is an essential component that engages and disengages parts of the movement, particularly for winding, time-setting functions, or the chronograph mechanism.

Clutch Wheel

The clutch wheel in a watch connects the chronograph mechanism to the main gear train, allowing it to operate.

Coin Edge Bezel

A coin edge bezel features a finely serrated, milled edge, providing a classic appearance and enhanced grip.

Coin Edge Crown

A coin edge on a watch refers to the decorative, milled edge of the bezel or crown, offering a classic look and improved grip.

Coke Bezel

The Rolex GMT-Master II reference 16760 introduced a new GMT movement allowing independent adjustment of the 12-hour and 24-hour hands, as well as a new bezel colour scheme known as the “Coke” bezel, which is red and black.

Colimaçon Finish

Colimaçon is a decorative finishing technique in watchmaking that creates a spiral or snail-shaped pattern, reminiscent of a spiral staircase.

Collet

A collet is a metal band or ring used in watches to secure the end of a balance spring.

Collet Press

In watchmaking, a collet is a small, split ring or sleeve that holds or secures a part precisely.

Complications

In watches, a complication refers to any feature that goes beyond the basic display of hours, minutes, and seconds. These additional functions necessitate extra gears and parts, making the watch movement more complex. Examples include simple additions like a date window and more complex functions like a chronograph, perpetual calendar, or moon phase indicator.

Complications Stack

In mechanical watches, a "complications stack" refers to the collection of additional complex components beyond basic timekeeping (hours, minutes, seconds) incorporated into a watch's movement. These functions can range from simple date displays to highly complex features like a perpetual calendar or split-seconds chronograph, highlighting the intricate engineering required to integrate multiple complications into a single timepiece.

Compression Gasket

A compression gasket is a rubber or silicone ring compressed between two parts of a watch, such as the caseback and the case, creating a watertight and airtight seal that protects the internal movement from dust, moisture, and pressure changes.

Compression Ring

This is a key component of a high-pressure case architecture in watches, such as Rolex's Ringlock system, which utilises the ring to bear and distribute immense water pressure, ensuring the watch remains waterproof at extreme depths.

Compression Tool

In watchmaking, a compression tool refers to the tool used to press down the case back of a watch to secure it, while "compression" also describes the Super Compressor design, where water pressure compresses the case to create a better seal.

Conversion Case

This is an aftermarket case that has been modified to accommodate alternative parts.

Crown

The crown is the small knob located on the side of the watch case (typically at the 3 o'clock position) used for setting the time and date, winding the mainspring in mechanical watches, and adjusting other complications such as the chronograph or moonphase. The type of crown, such as screw-down or push-pull, can also influence the water resistance of the watch.

Crown Guard

A crown guard is a protective feature on the watch case that shields the crown from accidental impacts, preventing damage or breakage.

Crown Knurling

Crown knurling is a pattern of lines or grooves milled into a crown to provide grip. These knurled patterns can also serve as decorative elements on watch cases, such as on a knurled bezel.

Crown Position

The crown position refers to the various settings in which a crown can be moved for different functions. Typically, these include Position 0 (or neutral) for normal wear, Position 1 for winding the mainspring and setting the date, and Position 2 for setting the time.

Crown Seal

The crown seal ensures that the movement of the crown does not cause damage to the casing.

Crown Stem

The crown is the knob used to wind the watch and set the time, while the crown stem is the rod that connects the crown to the watch's internal movement. By turning the crown, the stem rotates, transmitting motion to the watch's gears to wind the mainspring or adjust the hands.

Crown Tube

A crown tube is a small, hollow cylinder on the side of the watch case through which the stem of the winding crown passes to connect to the movement.

Crystal AR

Anti-reflective (AR) coatings can be applied to both sapphire and mineral crystals.

Crystal Lift

Crystal lift is a technique for removing and inserting watch crystals without disassembling the watch.

Crystal Press

A crystal press is a specialised tool used to install or replace a watch crystal, most commonly one with a gasket or compression fit.

Crystal Scratch Test

A watch crystal scratch test is a method used to determine the durability of a watch crystal. It typically involves a simple and non-invasive test to establish if the crystal is genuine sapphire.

Cushion Case

A cushion case is a watch case shape that features square sides with rounded edges, resembling a pillow. This design combines the clean lines of a square with the soft curves of a circle, resulting in a distinct look often associated with casual elegance.

Cushion Lugs

Cushion lugs are watch lugs that have a rounded square or "pillow-like" shape, resembling a cushion case. They are often found on vintage dive watches and are designed to blend seamlessly with the case.

Cyclops

A cyclops is a small, convex magnifying lens placed over the date window to make the date easier to read.

Cyclops AR

The term "Cyclops" refers to a magnifying lens that is placed over the date window on a watch, making the date easier to read. The "AR" stands for anti-reflective coating, which is a layer applied to both the Cyclops lens and the watch crystal. This coating reduces glare and enhances legibility in various lighting conditions.

Cyclops Glue

Cyclops glue is a specialised, high-strength adhesive used to bond a small magnifying lens (the "Cyclops") to a watch crystal, allowing the date to be more easily read. The glue must be strong enough to secure the lens permanently, but also removable with heat if necessary.

Cyclops Lens

A Cyclops lens in a watch is a small, convex magnifying lens positioned over the date window to enhance readability. It is a functional feature, often made of scratch-resistant sapphire crystal, that magnifies the date display by approximately 2.5 times its original size.

Date Corrector

A date corrector in a watch is a physical button or a specific position of the crown used for manually adjusting the date. It allows the wearer to advance the date displayed on the dial without needing to wind the watch hands through a full 24-hour cycle.

Date Jumper

In watchmaking, a "date jumper" is a small lever, often shaped like a flat spring, that engages with the date wheel to advance it by one day at the correct time, typically at midnight.

Date Magnifier

A date magnifier on a watch, commonly known as a cyclops, is a small convex lens positioned over the date window to enhance readability of the date.

Date Ring

In watches, a "date ring" can either refer to the rotating bezel used to track time or, in terms of internal components, the date disk, which is the toothed wheel that displays the date.

Date Wheel

A date wheel is a rotating disk inside a watch that shows the date, typically through a small window on the dial. It is an essential component of the watch's movement, advancing each day to display the correct date.

Date Window

The date window is a small opening on a watch dial that displays the current date, typically located at the 3, 4, or 6 o'clock position.

Day Jumper

A "jumping hour" watch displays time using a disk with numbers that "jump" to the next hour instantaneously, rather than using a traditional analogue hand that moves gradually. This mechanism is often a complication found in high-end mechanical watches, featuring a window on the dial that shows the current hour in a digital format, with the disc changing precisely at the end of each hour.

Day Wheel

A "day wheel" in a watch is a rotating disc that displays the day of the week, forming part of the day-date complication that also shows the numerical date. It advances every 24 hours, typically changing around midnight, to indicate the correct day of the week in a window or on a sub-dial.

Day-Date Window

A day-date window in a watch is a small display on the dial that shows both the day of the week and the numerical date of the month. This feature is considered a "complication" because it provides information beyond just the time, allowing the wearer to see both pieces of information at a glance.

Day/Date Wheel

The day/date wheel complication shows both the current date and the day of the week.

Decorated Rotor

A decorated rotor features intricate engravings, logos, or gemstones for aesthetic appeal.

Demagnetizer

A demagnetizer for watches is a device used to eliminate magnetism from a watch's internal parts, which can cause it to run either fast or slow. This is usually achieved by exposing the watch to a strong, alternating magnetic field that scrambles and neutralises any built-up magnetic charge—especially in the hairspring—allowing it to oscillate freely again.

Demag Field

The term "demag field" likely refers to a demagnetising field used to eliminate magnetism that has caused a watch's movement to become magnetised, leading to inaccuracies in timekeeping.

Deployment Clasp

A deployment clasp is a type of watch buckle that unfolds to open, creating an unbroken loop around the wrist. This design eliminates the need to unbuckle the strap each time you put the watch on or take it off.

Dial Arrow

In watches, a "dial arrow" can refer to either an arrow-shaped hour marker on the face or an arrow-tipped hand. Both designs enhance legibility, with the arrow hand specifically aiding in clearly indicating the time or a secondary time zone, while arrow markers add a bold visual element.

Dial Code

The term "dial code" in watchmaking refers to a part number or reference code used by manufacturers to identify a specific dial type, colour, or finish. These codes assist assembly workers and suppliers in identifying the correct dial for a particular watch model, especially since different dials may share the same movement and case.

Dial Dot

A "dial dot" in watches can refer to two things: a small, round hour marker on a watch face, or a small, double-sided adhesive pad used to secure a dial to the watch movement.

Dial Feet

In watchmaking, "dial feet" are small metal posts on the back of a watch dial that secure it to the watch movement. They align with specific holes in the movement and are held in place by small screws, preventing the dial from shifting or slipping inside the watch case.

Dial Feet Locator

A dial feet locator is a tool or method used by watchmakers to accurately measure the positions of the dial feet, ensuring that the dial is correctly aligned when installed onto the movement.

Dial Printing

Dial printing is a manufacturing process that applies a design onto a watch's face using a technique called pad printing or tampography.

Dial Refinishing

Dial refinishing is the process of restoring a watch dial to its original aesthetic by cleaning, repairing, and reapplying finishes to remove scratches, dents, and discolouration.

Dial Shims

Dial shims are thin metal or plastic pieces used to correct small gaps or misalignments between the dial and the watch movement. This ensures the dial sits correctly and functions properly. They are often employed to account for manufacturing tolerances and can prevent components, such as the hour wheel, from disengaging from the pinion that drives it.

Dial Spacer

A dial spacer is a ring, often made of plastic, that fits between a watch movement and its case. It fills gaps, stabilises the movement, and ensures proper alignment of the hands and dial.

Dial Texture

"Dial texture" refers to the pattern or surface treatment applied to a watch's face, creating a tactile and visual finish that impacts the watch's appearance and how it interacts with light. Common examples include the sunburst finish with radial lines, intricate engraved patterns of guilloché, and the linear or radial scratches found in brushed or linen dials.

Dial Texture Brush

A dial texture brush is a finishing technique that uses fine bristles to create a non-reflective, textured pattern on a watch dial, often in a linear, circular, or sunburst design. This "brushed" finish provides subtle texture, reduces glare, and gives the watch face a more dynamic and subdued appearance compared to a polished dial.

Diamond Bezel

A diamond bezel is a decorative ring surrounding the watch face, adorned with diamonds, giving the watch a luxurious and high-end appearance.

Diamond Crown

The diamond crown is a small ribbed knob or a rounded cut diamond, typically found at the 3 o'clock position.

Diamond File

A diamond file is an abrasive tool used for fine, precise work on watch parts. It is made by embedding diamond grit onto a steel base.

Direct Drive

Direct drive refers to a mechanical feature where the second hand moves in one-second increments. It can also describe a specific Seiko Kinetic movement that allows the wearer to manually wind the crown to generate power and monitor real-time power generation on a separate indicator hand.

Dive Bezel

A dive bezel is a rotating, external bezel on a watch that serves as a safety and timing tool for divers. It features a 60-minute scale with unidirectional rotation (typically counterclockwise) that prevents accidental overestimation of dive time.

Dive Timer

A dive timer is a feature on a watch, most often a unidirectional rotating bezel, that enables a diver to track the amount of time spent underwater.

Diver Clasp

A diver clasp is a specialised type of watch clasp designed for dive watches. It includes a built-in extension to adjust the bracelet length over a wetsuit. These clasps often feature a ratchet mechanism, allowing for quick, on-the-go adjustments without needing to remove the watch.

Diver Extension

A diver extension is a feature on dive watch bracelets that provides an adjustable section of links to allow the watch to be worn over a wetsuit. It works by unfolding or extending a part of the clasp, typically adding a few extra centimetres of length to accommodate bulky dive gear.

Domed Bezel

A domed bezel in watches is a smoothly curved ring surrounding the crystal, providing a classic look and often polished to a high-gloss finish. Unlike flat or smooth bezels, the domed shape has a soft, rounded profile, adding vintage charm and elegance to the watch.

Domed Crystal

A domed crystal is a transparent protective cover for the dial, featuring a curved, outward-bulging surface. This curvature can vary from subtle to pronounced, giving the watch a classic or vintage look while creating unique light refractions that may distort the dial at certain angles. Domed crystals can be made from acrylic, mineral glass, or sapphire.

Domed Indices

"Domed indices" refers to applied hour markers on a watch that have a rounded, domed top, giving them a three-dimensional, bubble-like appearance. This is distinct from domed crystals, which refer to the arched shape of the glass protecting the watch face, although they often complement each other visually.

Domed Indices Gold

"Domed indices gold" describes markers on a watch dial that have a curved, domed surface and are made of gold.

Donor Watch

In watchmaking terminology, a "donor watch" refers to an older watch that serves as a source for its functional parts, such as the movement, which can then be used in a new or custom-built watch, often called a marriage watch. This practice is common when recovering a valuable or unique movement from a watch whose case is in poor condition or when a watchmaker aims to create a custom piece featuring a specific movement.

Double AR

"Double AR" refers to double-sided anti-reflective (AR) coating on the crystal, which reduces glare and makes the dial easier to read.

Double Beat

In watchmaking, "Double Beat" typically refers to watches equipped with two independent oscillators (balance wheels and hairsprings). These oscillators synchronise through resonance, resulting in improved timekeeping accuracy. Less commonly, it can refer to a double balance wheel mounted on a single staff, which enhances stability by increasing the moment of inertia and compensating for issues arising from asymmetrical balance springs.

Double Dome Sapphire Crystal

A double-dome sapphire crystal is a watch crystal that features curvature on both the top and bottom surfaces. This design minimises distortion and magnification when viewing the watch dial from an angle, providing a clearer and wider viewing angle compared to a single dome crystal, which has a flat bottom.

Double Quick-Set

A watch with a "double quick-set" function allows the wearer to independently and quickly set both the day and date, eliminating the need to manually cycle the hour hand through a full 24-hour rotation for each adjustment.

Drilled Lugs

Drilled lugs are holes drilled all the way through the lugs, which are the parts of the watch case that attach to the strap.

Dust Cap

A dust cap can refer to either a protective cover used during repairs or a component of the watch case that shields the movement from debris.

Dust Cloth

A "dust cloth" in the context of watches is a soft, lint-free cloth—most commonly a microfiber cloth—used to clean and polish the watch's surfaces without scratching them. It effectively removes fingerprints, dust, and grime, keeping the watch clean and protecting its finish, particularly on delicate, polished metal and crystal surfaces.

Dust Cover

In watches, a "dust cover" is a protective component, often a metal cap, that fits over the movement to shield it from dust, dirt, and other contaminants during servicing or from external factors.

Ebauche

An ébauche is a watch movement kit that consists of the basic components, such as plates, bridges, and wheels. However, it is incomplete and unassembled.

Elastomer Strap

An elastomer strap for a watch is made from an elastic, rubber-like material, such as synthetic rubber (FKM) or silicone. These straps are known for being durable, flexible, water-resistant, and comfortable.

Electric Timer

An electric timer typically refers to a stopwatch function that measures and displays elapsed time separately from the main time. This function is operated by buttons that start, stop, and reset the timer, distinguishing it from a regular electric watch.

Enamel

Enamel is a glassy coating applied to a metal dial plate that is fused onto it through high heat. This process creates a durable, scratch-resistant, and often glossy surface. Known as vitreous enamel, it involves firing powdered glass onto the metal base until it melts and fuses, resulting in vibrant colours and designs.

Enamel Crackle

Enamel crackle is deliberately created by fusing two layers of glass enamel with different expansion rates. As the top layer cools, it cracks into a web-like pattern.

Enamel Dial

An enamel dial is made by fusing powdered glass onto a metal plate at high temperatures, which creates a smooth, durable, and glossy surface.

End Cutter

An end cutter is a type of plier used in watchmaking for making close, sharp cuts on wires. It is particularly useful for shortening watch winding stems or other fine wires to the appropriate length.

Engine Turning

Engine turning is an intricate mechanical engraving technique that cuts precise, repetitive patterns into metal watch parts, such as dials, cases, and movements.

Engraved Case Back

An "engraved case back" refers to the engraved lettering and designs on the solid metal cover at the back of a watch case.

Engraved Indices

"Engraved indices" in watchmaking refers to hour markers that are physically cut into the watch dial rather than being printed or applied. This technique creates a tactile and durable marker, often filled with a contrasting material like paint or lacquer for improved legibility.

Engraved Rotor

An engraved rotor is a semicircular weight found in automatic watches, which is decorated with a design or text and is visible through the watch's case back. Its primary function is to automatically wind the watch's mainspring as it spins with the movement of the wearer's wrist, while the engraving serves as a decorative element that enhances the visual appeal and personalisation of the watch.

Epsilon Crown

The "Epsilon Crown" is a specific type of electro-mechanical crown designed by the watch brand Ressence. It represents a proprietary technology that combines the precision of mechanical watchmaking with the functionality of modern technology.

Epsilon Dial

In vintage watch terminology, an "epsilon dial" does not specifically refer to the design of a dial. Instead, it is a suffix letter (E) indicating that a watch movement features a gilt finish, meaning the movement plates are coated with a gold alloy. This detail pertains to the movement inside the watch and is used as an identifier by collectors, particularly in relation to Smith's watches.

Escape Fork Jewel

An escape fork jewel is a synthetic ruby or sapphire bearing that reduces friction and wear in the moving parts of a mechanical movement, thereby improving accuracy and longevity.

Escape Lever

The escape lever is a mechanism that controls the rate at which the mainspring unwinds, releasing energy in a controlled manner to the timekeeping component, which is the balance wheel.

Escape Wheel

The escape wheel is a toothed wheel in a mechanical watch's escapement. With each tick, it is locked and unlocked by the pallet fork, allowing the gear train to advance by a fixed amount.

Escape Wheel Pivot

The escape wheel pivot is a tiny, cylindrical metal post located on the axle of the escape wheel in a mechanical watch.

Escapement

An escapement is a mechanical linkage in a mechanical watch that regulates the release of energy from the mainspring, keeping the watch's timekeeping element, the balance wheel, oscillating at a steady rate.

Etched Dial

An etched dial features a design that is either plain or engraved into the surface of the dial.

Exhibition Case Back

An exhibition case back is a watch's transparent cover on the back, typically made of sapphire crystal, that allows wearers to view the watch's internal movement and intricate mechanisms. This feature enables admirers to appreciate the craftsmanship, complexity, and artistry of the watch's mechanical workings and is often found on high-end and automatic watches.

Exhibition Dial

An "exhibition dial" is an informal term for a transparent case back on a watch, allowing the wearer to see the detailed internal movement.

Exhibition Rotor

An "exhibition rotor" in watches is a semi-circular, oscillating weight that is visible through a transparent case back. It automatically winds the mainspring of a mechanical watch.

Explorer Bezel

An Explorer bezel is a fixed, 24-hour bezel on the Rolex Explorer II watch, designed to work with its 24-hour hand. Its primary purpose is to display a second time zone or to clearly indicate AM/PM.

Explorer Homage

An "Explorer homage" refers to a watch that pays tribute to the classic design of the Rolex Explorer, usually at a significantly lower price point. These watches draw inspiration from the original's key design features, such as the 3-6-9 Arabic numeral dial and Mercedes hands.

F6922 Movement

The Orient F6922 movement is an in-house mechanical automatic watch movement produced by Orient Watch Co., LTD.

F6922 Rotor

The F6922 Rotor is a component of the Orient Calibre F6922, a specific type of self-winding (automatic) watch movement manufactured by Orient.

FKM

FKM stands for Fluoroelastomer, which is a durable material capable of withstanding high temperatures, harsh chemicals, and abrasion.

Faceted Hands

Faceted hands refer to a style of watch hand, most commonly the Dauphine hand, that has a central ridge and sharp, angular edges to catch the light.

Faded Bezel Insert

A faded bezel insert, often referred to as a "ghost bezel," is a naturally occurring patina on vintage watches, where the bezel's colour has faded due to exposure to sunlight, salt, and general wear over time.

Fake Crown

A "fake crown" refers to counterfeit branding, particularly the Rolex crown logo, found on both the dial and the winding crown of the watch.

Fake Detection

Fake detection in watches involves the authentication process that examines the details of a watch to differentiate a genuine product from a counterfeit.

Fake Lume

"Fake lume" refers to counterfeit or poorly made luminous material used on a watch's hands and hour markers.

Fake Parts

In the context of watches, "fake parts" are unauthorised copies or substitutes that have been incorrectly identified or presented as genuine by the original manufacturer.

Fat Spring Bar

A fat spring bar in watches is a thicker and stronger version of a standard spring bar. It has a more robust body and often features thicker tips, providing a more secure hold for heavy or durable watches.

Finishing

Finishing refers to the decorative and functional processes involved in polishing, engraving, and assembling watch components to enhance their aesthetics and precision.

Flat AR Sapphire

A flat AR sapphire crystal is made of hard, scratch-resistant sapphire glass. It is flat on both sides and features an anti-reflective (AR) coating that reduces glare. The flat shape provides a clean aesthetic without magnification, while the AR coating enhances dial legibility by minimising reflections and allowing for a clearer view of the watch face in various lighting conditions.

Flat Bezel Insert

A flat bezel insert is a component of a watch that fits into the bezel and has a flat profile, as opposed to a sloped one.

Flat Crystal

A flat crystal in watches has a completely level, smooth surface from edge to edge, without any curvature. This design offers superior optical clarity and durability, as it sits flush with the watch case, resulting in less light reflection and a reduced risk of damage.

Fluted Bezel

A fluted bezel is a decorative ring on a watch with a ridged or grooved pattern that catches the light. Initially, this design served a functional purpose by helping to securely screw the bezel to the watch case, thereby improving water resistance. Today, the grooves are primarily decorative.

Fluoro Strap

A Fluoro Strap, also known as an FKM (Fluoroelastomer) strap, is a durable and high-performance watch strap made from a type of synthetic rubber known for its exceptional resistance to heat, chemicals, oil, and ageing. This makes it ideal for demanding environments, as it is both tough and comfortable, remaining flexible and soft against the skin without becoming sticky or attracting dust.

Fluoroelastomer Strap

A fluoroelastomer strap is a high-performance synthetic rubber band for a watch, known for its outstanding durability and resistance to heat, chemicals, and UV rays.

Flyback Button

A flyback button on a watch allows the user to reset the chronograph and immediately start a new timing interval with a single push. This feature combines the stop, reset, and restart functions.

Flyback Chrono

A "flyback chrono" is a watch with an advanced chronograph feature that allows the user to reset and restart the stopwatch instantly with a single button press, without needing to stop it first.

Flyback Lever

A flyback lever is a complication in watches that enables the wearer to stop, reset, and restart a chronograph's timing function with a single press of a pusher. This "flyback" action is particularly advantageous for timing successive events, such as flight legs for pilots or laps in a race, as it saves time and enhances accuracy.

Flying Tourbillon

A flying tourbillon is a watch mechanism that, unlike a traditional tourbillon, is supported from only one side. This design creates the illusion that it is "flying" freely without an upper bridge.

Fold Clasp

A fold clasp in watches is a type of fastener that secures the strap or bracelet by folding it over itself, providing both security and ease of use.

Fold Deployant

A fold deployant, also known as a deployment clasp, is a type of watch buckle that opens and closes by folding. This design allows a watch to be put on and taken off easily without fully unbuckling it.

Fold-Over Clasp

A fold-over clasp, or deployant clasp, is a watch closure mechanism that unfolds to open and folds back over itself to close securely.

Full Ceramic Case

A timepiece with a full ceramic case is constructed from a high-tech, non-metallic material, typically zirconium oxide (\(ZrO_{2}\)). This material is known for its exceptional hardness, scratch resistance, lightweight feel, and hypoallergenic properties.

G10

NATO watch straps, also referred to as "NATO straps" or "G10 straps," were developed by the UK Ministry of Defence.

Gasket

The gasket plays a crucial role in any mechanical watch. It provides a seal that protects the watch's delicate internal mechanisms from external elements such as dust, moisture, and pressure changes.

Gear Ratio

Gear ratio is the comparison of the number of teeth on a "driver" gear to the number of teeth on a "driven" gear. This ratio determines how many times the input gear must turn for the output gear to complete one rotation.

Gear Train

A watch's gear train comprises a series of interconnected wheels and pinions that transfer energy from the mainspring to the escapement. This system regulates the power release needed to drive the hands of the watch.

Geneva Seal

The Geneva Seal, also known as the Poinçon de Genève or Geneva Hallmark, is a quality certification for mechanical watches. It guarantees that the watch is made in the Canton of Geneva and adheres to strict standards for both quality and finishing.

Geneva Stripes

Geneva stripes, or Côtes de Genève, are a decorative, wave-like pattern of fine scratches etched onto the surfaces of watch movement parts, such as plates and bridges.

Gilt

In the context of watches, gilt refers to a vintage manufacturing process used on dials where the lettering and markers are created from the underlying exposed metal, often brass, beneath a black, glossy lacquer. This creates a mirror-like, golden-hued finish.

Glide Lock

The Glide Lock is a patented, tool-free adjustment system found on certain Rolex watch bracelets, especially on dive models like the Submariner and Sea-Dweller. It allows wearers to easily expand or contract the bracelet in small increments—typically up to 20 mm in total—by sliding a section of the clasp.

GMT

Greenwich Mean Time (GMT) is the time measured along the Earth's zero-degree line of longitude, also known as the prime meridian.

GMT Bezel

The GMT bezel, in conjunction with the GMT hand, plays a vital role in watches with a GMT function. This rotating bezel can be used to set a second or third time zone. Like the GMT hand, the GMT bezel displays 24 hours and is usually two-colored to differentiate between day and night.

GMT Crown Pull

The GMT hand can be set to the desired second time zone by pulling the crown to a different position, typically the first position, and rotating it to move the GMT hand independently of the main hands.

GMT Hand

A GMT watch features a 24-hour hand that indicates a second time zone, in addition to the standard hour, minute, and second hands. This differs from watches with multiple 12-hour-format dials, which is a common misconception.

GMT Insert

The GMT bezel insert is a rotating ring on a watch that has a 24-hour scale used to track a second time zone.

Green AR Coating

A green AR (anti-reflective) coating on a watch crystal reduces glare and enhances legibility. This optical coating appears green under certain lighting conditions, and while AR coatings reduce overall reflection, some formulations reflect light in specific colours, most commonly green.

Green Bezel

A green bezel is the outer ring of a watch that is colored green. This hue can serve both decorative and functional purposes. In watchmaking, green is often associated with nature, growth, and prosperity; it can also refer to specific models like the Rolex Submariner "Kermit."

Green Dial

A green dial is a watch face that features a green colour, which has become a popular and versatile design choice. Green dials evoke associations with nature, growth, and harmony, while also representing luxury, freshness, and sophistication.

Guilloché Bezel

A guilloché bezel is adorned with intricate, decorative patterns engraved into its surface using a technique called engine turning. This labour-intensive method, known as guilloché, involves using a special machine, like a rose engine, to create precise, repetitive patterns that catch the light and add depth and texture to the watch.

Guilloché Center

A "guilloché centre" in watches refers to the dial or case decorated with intricate, repetitive, often geometric patterns, mechanically engraved using the guilloché technique.

Guilloché Dial

A guilloché dial features an intricate, repetitive pattern created through mechanical engraving with a rose engine or a similar machine. These decorative designs, such as wavy lines, spirals, or grids of tiny squares, add texture and depth, refracting light in complex ways and are characteristic of traditional high-end watchmaking.

Guilloché Hands

In watches, "guilloché" pertains to the intricate, repetitive, and geometric patterns mechanically engraved onto the dial, case, or movement, rather than specifically referring to the watch hands themselves.

Guilloché Pattern

Guilloché is an intricate, repetitive decorative pattern that is engraved onto various watch parts, such as dials and movements, using specialised machines known as engine-turning lathes.

Hacking Lever

A hacking lever is a component in a mechanical watch that stops the balance wheel when the crown is pulled out, causing the second hand to stop moving.

Hacking Pin

A hacking pin in a watch is part of the "hacking" or "stop-seconds" mechanism that halts the seconds hand when the crown is pulled out to set the time. This feature allows for precise synchronisation with a reference time, which is especially useful for military or navigation purposes.

Hacking Seconds

Hacking seconds is a feature in a watch where the seconds hand stops moving when the crown is pulled out to set the time, facilitating precise synchronisation with a reference clock.

Hand Alignment

Hand alignment refers to the accurate positioning of the hour, minute, and second hands so that they are perpendicular to the dial and parallel to each other.

Hand Friction Washer

A hand friction washer, also known as a dial washer, is a component in the dial train of a watch. It provides friction to prevent the hour wheel from rising and disengaging from the minute wheel pinion, keeping the hour wheel in place when the watch is turned dial-down.

Hand Hole Punch

A hand hole punch is a specialised tool used for creating or adding holes to a watch strap, typically made of leather.

Hand Lume

Hand lume is a luminous material applied to a watch's hands, allowing them to glow in the dark for better visibility in low-light conditions.

Hand Press

A hand press is a tool used to precisely set watch hands onto the movement's posts.

Hand Set Tool

A hand-set tool is a specialised instrument used to accurately press watch hands (such as the hour, minute, and seconds hands) onto the posts of the watch's movement.

Hands

Hands are slender, pointed indicators on a watch dial that rotate to display the time. The most common are the shorter hour hand, the longer minute hand, and often a thin seconds hand.

Hardened Steel

Hardened steel is steel that has undergone a heat treatment process to significantly increase its resistance to scratches and impacts, making it much more durable than standard stainless steel.

Hardlex Crystal

Hardlex crystal is a proprietary, hardened mineral glass developed by Seiko. It offers increased resistance to scratches and shattering compared to standard mineral glass.

Hardlex Dome

A Hardlex Dome is a dome-shaped watch crystal made from Seiko's proprietary hardened mineral glass, providing both scratch and shatter resistance.

Hardlex Polish Kit

A Hardlex polish kit is a set of tools and abrasives designed to remove scratches from Hardlex watch crystals, which are made of Seiko’s hardened mineral glass.

Helium Escape Valve

A helium escape valve (HEV) is a safety feature found in professional saturation diving watches. It automatically releases trapped helium from inside the watch during decompression.

Helium Gasket

The term "helium gasket" in relation to watches is actually a misnomer for a helium escape valve. This one-way valve is found on professional dive watches and is designed to protect the timepiece from damage during saturation diving.

Helium Release

A helium release is a one-way valve incorporated into the case of a professional dive watch. It allows helium gas to escape during the decompression process, preventing potential damage to the watch.

Helium Test

The helium test is a leak detection method that uses helium gas to identify small leaks or to assess the functionality of a Helium Escape Valve (HEV). This test checks if the watch can withstand saturation diving without risking an explosion. During the test, helium gas is pressurised inside a component, and a sniffer detector is used to locate any leaks, which may indicate a weak seal.

Hesalite Crystal

Hesalite crystal, also known as acrylic glass, Plexiglass, or PMMA, is used as a watch crystal. It is lightweight, flexible, and resistant to shattering upon impact. However, hesalite is softer and more susceptible to scratches compared to mineral or sapphire crystals.

High Beat Movement

A high beat movement is a mechanical movement that oscillates at a frequency of at least 28,800 vibrations per hour (vph), or 4 Hertz (Hz). This increased frequency results in a smoother, more continuous sweep of the second hand and can enhance the watch's accuracy.

High Dome

In watches, a high dome refers to a crystal with a pronounced and exaggerated curvature. This type of domed crystal is typical of vintage watches and creates a striking three-dimensional effect. While it offers a warm aesthetic, it can also cause significant distortion or magnification when viewed from an angle.

Homage Build

A homage build refers to a timepiece intentionally designed to pay tribute to the style and aesthetics of an iconic, often more expensive, luxury watch, without being a replica.

Homage Indices

Homage indices are the hour markers on a watch inspired by or directly emulating the design of an iconic or historically significant timepiece.

Homage Watch

An homage watch is a new timepiece that honours a classic watch design while not being an exact copy. It is generally considered legal as it features distinct branding, uses modern materials, and often incorporates minor design changes.

Hour Hand

The hour hand is the shorter hand on an analogue watch or clock that indicates the hour. It moves slowly, taking 12 hours to complete one full rotation of the dial.

Index Alignment

Index alignment refers to the accuracy with which the hour and minute hands align with the hour markers on the dial.

Indices

Indices are the markers on the watch face that indicate time, such as the positions for hours and minutes. These markers can be printed directly onto the dial or applied as raised elements, and they come in various styles, including Arabic numerals, Roman numerals, baton markers, or dots.

Inner Bezel

An inner bezel is a rotating ring located beneath the watch crystal, controlled by a separate crown or pusher.

Inner Bezel Gasket

An inner bezel gasket is a rubber or plastic seal that sits between the internal bezel and the watch's crystal or case, ensuring that the watch is watertight and dust-tight.

Inner Dial Ring

An inner dial ring, also known as a chapter ring, is found on the inner part of a watch's dial. This ring features markers or numbers that enhance legibility, particularly for smaller minute markers.

Inner Gasket

An inner gasket is a small, flexible ring, typically made of rubber or silicone, that creates a seal between components to prevent water, dust, and other contaminants from entering the watch case.

Integrated Bezel

An integrated bezel refers to a bezel that is part of the case, with no visible lugs, providing a seamless design.

Integrated Bracelet

An integrated bracelet is a watch band that seamlessly flows from the watch case, making it appear as a single, unified piece. Unlike traditional designs with separate lugs, the first link of an integrated bracelet extends from the case, creating a continuous line and a modern look.

Integrated Crown

An integrated crown is a crown with built-in, permanent guards that are machined directly into the watch case, resulting in a seamless, strong, and protected component.

Isochronism

Isochronism is a watch's ability to maintain a consistent rate of timekeeping, regardless of the amplitude of the balance wheel's oscillations.

Isofrane Keeper

An Isofrane keeper is the small loop that secures the excess length of an ISOfrane dive strap after it has been fastened. The term combines "Isofrane," a brand of durable, high-quality rubber dive straps, with "keeper," which is the standard term for the loop that holds the tail end of a watch strap.

Isofrane Strap

An Isofrane strap is a brand of premium, vulcanised rubber watch strap known for being soft, durable, and comfortable, especially for dive watches.

Isofrane Vent

An Isofrane vent is a high-quality, ventilated dive watch strap known for its unique design and durability. The term "vent" refers to the ladder-style holes that provide ventilation, allowing the strap to breathe and keep the wrist cool.

Jubilee Bracelet

A Jubilee bracelet is a five-link watch bracelet originally introduced by Rolex in 1945 for the Datejust. It is characterised by three narrow, polished or satin-finished centre links flanked by two wider, more robust outer links, giving it a distinct, elegant, and flexible appearance compared to other styles.

Jubilee-Style Strap

A Jubilee-style strap is a five-link watch bracelet characterised by three narrow inner links flanked by two larger outer links.

Keyless Fork

The keyless works is the internal mechanism that allows the user to wind the mainspring and set the time using the winding stem and crown, eliminating the need for a separate winding key.

Keyless Lever

The keyless works is the mechanism that allows you to wind the watch and set the time by turning the crown, instead of using a separate key.

Keyless Works

The keyless works is the system of gears and levers that enables you to wind the watch and set the time using the crown, eliminating the need for a separate key. The term originated from early pocket watches that required a key, but the invention of the keyless mechanism eliminated this need.

Lume

Lume in watches is a shorthand term for the luminous, phosphorescent material applied to elements like the hands, hour markers, and dials to make the watch visible in low-light conditions. It serves both a functional and aesthetic purpose, allowing the time to be legible in the dark by absorbing light and then emitting it slowly over time.

Lume Applicator

A lume applicator is a tool or method used to apply the luminous lume material to watch hands, dial markers, and other components.

Lume Charge

A lume charge is the process by which a watch's luminous material, or "lume," absorbs light energy and then emits it over time to glow in the dark. This charging is a non-radioactive process, commonly found in modern watches using compounds like Super-LumiNova, enabling the watch to be readable in low-light conditions.

Lume Duration Test

A watch's lume duration test is a method used to evaluate how long its luminescent markings (such as hands and hour markers) remain visible after being charged with light.

Lume Pip

A lume pip is a luminous dot or marker on a watch's bezel, usually located at the 12 o'clock position, that glows in the dark after exposure to light. Its main function is to serve as a reference point on dive watches.

Lollipop Hand

Lollipop hands are characterised by their circular, lollipop-like tips, which provide a playful and eye-catching design element. This whimsical design is commonly found on sports and dive watches, where the bold shape ensures excellent legibility in various conditions.

Lug

A lug is the protruding extension on the side of the watch case where the strap or bracelet attaches.

Lug Curve

The lug curve refers to the shape of the lugs, which are the metal protrusions on the sides of the watch case where the strap attaches. A downward-turned lug curve is designed to follow the natural contour of the wrist, improving comfort and wearability, and is frequently seen on dressier watches.

Lug Finish

Lug finish refers to the final decorative treatment applied to the watch lugs, which are the projections on the watch case where the strap or bracelet attaches. This finish is designed to match the overall aesthetic of the watch, with common types including polished, brushed, or a combination of both.

Lug-to-Lug

Lug-to-lug refers to the distance from the tip of the top lug to the tip of the bottom lug, measured vertically. This dimension affects the wearability and comfort of the watch. Common lug-to-lug distances range from 46-50mm, measured parallel to the strap. It is crucial for ensuring a proper fit of the watch on the wrist relative to the case diameter.

Lug-to-Lug Distance

The lug-to-lug distance is the measurement from the outermost tip of one watch lug to the tip of the opposite lug. Lugs are the parts of the watch case where the strap or bracelet attaches. This measurement indicates the vertical length of the watch on the wrist, influencing how it fits and wears. It is a crucial factor in determining whether a watch is the right size, as a watch with a long lug-to-lug distance may extend beyond the edges of a smaller wrist.

Main Crown

The main crown of a watch is the small knob located on the side of the case. It is used for winding the mainspring, setting the time and date, and operating other functions.

Main Plate

The main plate is the large, flat foundation plate of the movement, where all other components are mounted and secured.

Mainspring

The mainspring is a coiled metal strip that serves as the power source for the watch, storing and releasing energy to keep it running.

Mainplate Holes

Mainplate holes refer to the precisely machined holes in the mainplate of a watch movement.

Matte

Matte finishes are created through methods such as micro-bead blasting, sandblasting, or fine brushing, which diffuse light instead of reflecting it. This results in a soft, non-glossy surface that enhances readability and offers a utilitarian, tool-watch character.

Matte Bezel

A matte bezel features a flat, non-reflective surface that absorbs light.

Matte Dial

A matte dial has a non-reflective, flat finish that reduces glare, thereby improving legibility. It is created using techniques like sandblasting or textured paint, resulting in a subdued, utilitarian aesthetic often found in tool and military watches.

Mecha-Quartz

A Mecha-Quartz watch is a hybrid mechanical-quartz chronograph that employs a quartz movement for precise timekeeping alongside a mechanical module for chronograph functions.

Mecha Flyback

A Mecha-Quartz flyback watch combines a mechanical chronograph module with a quartz timekeeping movement. This design offers the instant reset and restart of a traditional flyback function while maintaining the precision of quartz.

Mercedes Hands

Mercedes hands are a style of watch hands characterised by a distinctive three-pronged star shape on the hour hand, resembling the Mercedes-Benz logo.

Mesh Bracelet

A mesh bracelet is a watch band made from tightly woven, interwoven metal wires, typically stainless steel. It is also referred to as a Milanese bracelet.

Mesh Insert

A mesh insert in a watch is a type of flexible, breathable watch band made from tightly woven metal wires, usually stainless steel. This design is commonly known as a Milanese bracelet or Milanese loop.

Mid-Size Bezel

A mid-size bezel refers to the type of bezel used on mid-size watches, which are smaller than full-size or oversized models but larger than women's sizes.

Mid-Size Case

A mid-size case generally describes a case diameter that is smaller than standard but larger than small, typically ranging from about 34mm to 41mm. This size is popular for offering a balanced look suitable for a variety of wrist sizes.

Milanese

Milanese watch bands are named after the Italian town of Milan, where they originated. These mesh straps are noted for their unique design, which adds a distinctive look to any watch.

Mineral AR

Mineral AR in watches refers to a mineral crystal watch face that has an anti-reflective (AR) coating applied to it.

Mineral Crystal

Mineral crystal is a protective transparent cover made of ordinary glass that has been heat-treated to enhance its scratch and shatter resistance. It is more durable than acrylic but less scratch-resistant than sapphire.

Mineral Dome

A mineral dome in watches is made from tempered glass mineral and features a curved, outward-bulging surface.

Minute Hand

The minute hand is the longer hand on a watch or clock that completes one full rotation every hour to indicate the minutes.

Minute Repeater

A minute repeater is a mechanical watch complication that chimes the time on demand, using a series of distinct tones for hours, quarter hours, and minutes.

Minute Track

A minute track is a ring of minute and second hash marks, typically printed on the dial or on the rehaut (the inner bezel ring), used for precisely reading the minutes and seconds.

Mirror Edge

The term "mirror edge" in watches refers to an extremely polished, mirror-like finish on the bevelled, or angled, edges of a watch movement's components, a detail known as mirror anglage.

Mirror Polish

A mirror polish is a highly reflective finishing technique that produces a smooth, mirror-like surface on a watch's case or movement parts.

Miyota 9015

The Miyota 9015 is a premium Japanese automatic watch movement renowned for its slim profile, high accuracy, and reliability.

Miyota 9075

The Miyota 9075 is a premium automatic mechanical watch movement featuring a "true" or "traveller's" GMT complication, allowing the local time hour hand to be adjusted independently in hourly increments.

Mod Community

The mod community refers to a group of enthusiasts who customise watches, often starting with affordable base models like those from Seiko, to create unique, personalised timepieces. Common modifications include swapping parts like the dial, hands, bezel, or crystal, and sometimes making more complex changes to the case or movement. Check out the Seiko Mod community on Reddit.

Mod Inspiration

Mod inspiration refers to the motivation behind customising a watch, which may involve changing its parts to create a unique timepiece or to replicate the look of a different, often more expensive, watch.

Mod Kit

A mod kit for watches is a collection of aftermarket parts used to modify a watch, allowing enthusiasts to build custom timepieces from scratch or alter existing ones by swapping components such as the dial, hands, case, bezel, and strap.

Mod Services

Mod services in the watch industry refer to services that modify or customise a timepiece. This can include changes to its appearance, adding functionality, or building a unique watch from aftermarket parts.

Monster Case

A Monster case refers to the distinctive, chunky, and aggressively styled case of the Seiko Monster diver's watch line, characterised by a shrouded bezel that protects the rotating bezel from impacts.

Movement Brush

A movement brush is the process of finishing a watch's internal components to create a matte, non-reflective surface with fine lines, as opposed to a polished, shiny finish.

Movement Dust Cover

A protective cap or tray used by watchmakers to shield the delicate internal parts of a watch from dust and debris during assembly, repair, or storage.

Movement Holder

A component that secures and protects the watch's internal mechanism, known as the movement or "calibre," inside the case.

Movement Overhaul

A comprehensive service that involves completely disassembling a mechanical watch movement to clean, inspect, repair, and lubricate each component.

Nautilus Case

A Nautilus case refers to a watch case design, famous for the Patek Philippe Nautilus, inspired by the shape of a ship's porthole. Its defining features include a distinctive, rounded octagonal bezel, an integrated case and bracelet with no visible lugs, and historically, a monobloc or two-part construction secured by four lateral screws.

Nautilus Homage

A Nautilus homage is a watch inspired by the design of the Patek Philippe Nautilus. It features similar elements, such as the porthole-shaped case, octagonal bezel, and integrated bracelet, but has its own branding and is usually offered at a lower price point.

NATO

A durable, single-piece nylon strap that loops through the watch's spring bars.

NATO Quick-Release

A strap that combines the durability of a NATO-style strap with the convenience of tool-less attachment and detachment using a quick-release spring bar.

NATO Strap

A NATO strap is a durable, single-piece watch strap made of nylon that loops through the watch's spring bars for added security. This design ensures that even if one spring bar fails, the watch will remain attached to the wrist. NATO straps are lightweight, waterproof, and affordable, with a wide variety of colours and patterns available.

No Crown Guard

A watch design that lacks protective shoulders or extensions to shield the crown.

No-Date Dial

A no-date dial is a watch that does not have a date window, resulting in a cleaner, more symmetrical, and minimalist design.

No-Date Stem

A no-date stem refers to the two-position stem found in watches without a date complication. This stem has two positions: one for winding the watch and another for setting the time.

No-Lume Bezel

A watch bezel that does not have any luminous or glowing material applied to its markings.

No-Lume Dial

A dial that lacks luminous material on its hour markers and hands, which means it will not glow in the dark. This design can provide a cleaner look and is often found in watches intended for daytime use, such as certain vintage sports or dress watches.

OEM (Original Equipment Manufacturer)

Refers to the original manufacturer of a product or component.

OEM Bezel

An OEM bezel is a genuine part made by the original brand of the watch.

OEM Dial

An OEM (Original Equipment Manufacturer) dial is the face of a watch manufactured by the OEM, meeting the original specifications for a specific watch brand.

OEM Hands

OEM hands refer to the hour, minute, and second hands produced by a manufacturer.

OEM Parts

Components such as the case, dial, hands, and movement made by the Original Equipment Manufacturer (OEM) are either sold as replacements for a specific brand or used to create new watches under a different brand.

Oil Bath

An oil bath can refer to two different concepts: either a standard watch service where parts are cleaned in an ultrasonic bath with oil and other fluids, or a unique design feature where the watch's dial and hands are submerged in a liquid, typically oil, to enhance clarity and legibility.

Onion Crown

This is a large, rounded, winding knob with a fluted or ridged surface that resembles an onion. This style originated in early pilots' watches, as its oversized and textured design allowed pilots to easily operate the crown to wind the watch and set the time while wearing gloves.

Open Heart

An open heart watch features a small aperture on the dial that reveals part of the mechanical movement, most commonly the balance wheel and escapement.

Orient Bambino

The Orient Bambino is one of the most popular Japanese dress watches in the world.

Oyster Bracelet

An Oyster bracelet is a robust, flat, three-piece link metal watch bracelet, originally patented by Rolex in 1947.

Painted Bezel

A painted bezel is one where the markings, numbers, or other design elements are applied to the surface using paint, such as luminous paint or colored enamel.

Painted Indices

In watchmaking, painted indices are hour markers that are directly applied to the watch dial with paint or lacquer, rather than being physical, attached metal pieces.

Paraflex Jewel

"Paraflex" is the name of Rolex's proprietary anti-shock system, which protects the watch's balance wheel by using a spring-loaded mounting system for the jewel bearings. It is designed to absorb impacts and disperse their energy, helping to prevent damage to the delicate balance of the staff pivots in case of shocks.

Patina

Patina refers to the natural, attractive changes and discolouration that occur on materials over time due to age, wear, and exposure to the elements. It's a superficial layer formed on metals through oxidation and other chemical reactions, making each vintage watch unique.

Pepsi Bezel

The red and blue "Pepsi" bezel is a defining feature of the GMT-Master II, designed to help pilots distinguish between daytime and nighttime hours in different time zones.

Pepsi GMT

A Pepsi GMT is a watch, typically from the Rolex GMT-Master or GMT-Master II collection, featuring a dual-colour bezel split between red and blue, representing day and night hours.

Perforated Leather Strap

A perforated leather strap for a watch has one or more holes punched along its length, primarily for enhanced ventilation and breathability.

Pin Buckle

A pin buckle, also known as a tang buckle or Ardillon buckle, is a traditional clasp that features a metal pin (tang) which inserts through a hole in the watch strap to secure it to the wrist.

Pin Gauge

A pin gauge is a precision tool consisting of a hardened cylindrical rod used to inspect and measure the size and spacing of holes, especially small ones, with high accuracy.

Pin Pusher

A pin pusher is a tool used to remove or insert the small pins that hold watch band links together, primarily for resizing or repairing metal bracelets.

Pinion Wheel

The pinion wheel is a small, toothed gear that meshes with a larger wheel to transmit motion and regulate timekeeping. It is a crucial component of a watch's gear train, transferring energy from the mainspring to the escapement and ultimately to the hands.

Plexi Dome

High-domed acrylic, often referred to as "bubble vintage."

Plexi Polish

Plexi polish refers to the process of using a polishing compound, such as Polywatch, to buff out scratches on a Plexiglass (acrylic) watch crystal.

Power Hack

Power hack, commonly known as watch hacking, is a feature in both mechanical and quartz watches that causes the seconds hand to stop when the crown is pulled out to set the time.

Power Reserve

A power reserve is the duration a mechanical watch can operate after being fully wound before it ceases to function.

Press-Fit Stem

A press-fit stem is a component that is installed in the watch's movement using a press-fit method, meaning it is pushed into place to create a secure, friction-based connection.

PRX

PRX is a collection from Tissot, where the name stands for "Precise and Robust." The "X" signifies 10 atmospheres (100 meters) of water resistance.

Quick Adjust Clasp

A quick-adjust clasp on a watch is a mechanism that allows for immediate, tool-free adjustments to the bracelet's length.

Quick Release Pins

Quick-release pins are a type of spring bar equipped with a small lever or knob, allowing for the rapid and tool-free exchange of watch straps.

Quick-Set Date

The quick-set date feature of a watch enables you to rapidly advance the date using the crown, without having to move the hands through a full 24-hour cycle.

Quartz Movement

A quartz movement is an electronic watch mechanism powered by a battery. It uses a quartz crystal that vibrates at a high frequency, converting these vibrations into an electric signal. This signal drives a motor, which turns the gears to move the hands and keep accurate time. Quartz movements are known for their precision and cost-effectiveness.

Ratchet Bezel

A ratchet bezel is a rotating outer ring on a watch case that moves in discrete, clickable increments. It is used for functions such as tracking elapsed time or displaying different time zones.

Ratchet Clasp

A ratchet clasp allows for quick and adjustable length changes without the need for tools, typically in small increments. This feature is particularly beneficial for divers who need to fit their watch over a wetsuit or for anyone whose wrist size changes with temperature.

Ratchet Wheel

A ratchet wheel is a notched gear located above the mainspring barrel. It tightens the mainspring to store energy.

Replica Dial

A replica dial is an unauthorised copy of an original luxury watch brand's dial, typically found in counterfeit or fake watches. These replicas are designed to mimic the appearance of genuine articles.

Replica Parts

Replica parts refer to components of an unauthorised copy of an authentic watch, including the dial, hands, case, or even the movement. These parts aim to replicate the look of a genuine luxury timepiece, but the original manufacturer does not produce them.

Regulator

A regulator is a small lever used to fine-tune the timing of a mechanical watch movement. Historically, regulator watches were prized for their high-precision timekeeping, and they continue to maintain this quality in modern designs.

Regulator Tool

The regulator tool or lever adjusts the effective length of the hairspring, allowing the watch to speed up or slow down its timing.

Rotor

In watches, a rotor is a semi-circular weight found in automatic, self-winding timepieces. It spins with the movement of the wearer's wrist to wind the mainspring and power the watch.

Rubber Bezel Gasket

A rubber bezel gasket is a small, ring-shaped seal that sits between the rotating bezel and the watch case, ensuring proper fitting and water resistance.

Rubber Strap

A rubber watch strap is a flexible and durable band made from synthetic or natural rubber. It is designed to be water-resistant and suitable for active lifestyles and sports.

Samurai Case

A Samurai case refers to a sharp, angular design found in certain Seiko dive watches, characterised by a bold, "sliced" look.

Samurai Mod

A Samurai Mod involves customising a Seiko Samurai watch by changing its parts to create a unique, personalised timepiece.

Sapphire Case Back

A sapphire case back is a transparent watch back made from synthetic sapphire crystal, allowing wearers to see the watch's internal movement.

Sapphire Crystal

Sapphire crystal is a transparent, synthetic material used in watches due to its extreme hardness and scratch resistance. It is a form of crystalline aluminium oxide, rated 9 on the Mohs scale, making it highly durable and providing a clear protective cover for the watch dial.

Scratch Build

In watchmaking, a "scratch build" refers to the process of creating a watch by fabricating most or all of its custom parts from raw materials, rather than assembling it from a pre-made kit. This may include making components such as the case, dial, hands, and crowns, although sometimes pre-made movements or commercially sourced detail parts are used.

Screw Down Back

A screw-down back is a caseback that screws directly into the watch case, providing a tight, watertight seal and enhanced protection from water and dust.

Screw Down Crown

A screw-down crown is a type of crown that screws into the watch case to create a watertight and dust-tight seal, improving the watch's water resistance. This feature is commonly found in diving and sports watches.

Seconds Collet

A seconds collet is the small, hollow tube on which the seconds hand is mounted in a watch movement, allowing it to be secured to the arbour of the fourth wheel.

Seconds Friction

Second's friction is the internal resistance that the movement must overcome for the gears to turn and move the hands, particularly the seconds hand.

Seconds Hand

The second hand is the hand that indicates the seconds of the day. It is typically the longest and fastest-moving hand on the watch face, completing a full rotation every 60 seconds.

Seconds Pinion

A seconds pinion is the small, toothed gear wheel in a mechanical watch to which the seconds hand is attached.

Seiko

Seiko is a Japanese manufacturer of watches, clocks, electronic devices, and semiconductors.

Seiko 5

Seiko 5 is an automatic movement featuring a day-date display at the three o'clock position, water resistance, a recessed crown at the four o'clock position, and a case and bracelet designed for durability.

Seiko 62MAS

The Seiko 62MAS refers to the model 6217-8000/1, which is Seiko's first professional dive watch, released in 1965. It is considered an iconic piece in the history of diving watches.

Seiko Mod

A Seiko Mod is a custom-built watch created using a genuine Seiko automatic movement, such as the NH35, combined with aftermarket parts like cases, dials, hands, and bezels. This customisation allows enthusiasts to tailor the watch's aesthetic and functionality to reflect their individual style while retaining the reliability of the Seiko movement at its core.

Seiko Monster

The Seiko Monster is a series of diving watches that enthusiasts refer to, originally created by Seiko in the year 2000 as part of their Seiko 5 Sports collection.

Seiko NH Series

The Seiko NH Series is a family of reliable, automatic mechanical watch movements designed for use by other brands, independent watchmakers, and hobbyists involved in watch modding.

Seiko Prospex

Seiko Prospex is a collection of timepieces that push every limit, catering to sports lovers and adventure seekers, whether they're underwater, in the sky, or on land. Prospex is short for "professional specification."

Seiko Sea Urchin

The Seiko Sea Urchin is a nickname for a series of entry-level dive-style automatic watches from the Seiko 5 line, specifically referring to models like the SNZF17.

Seiko Turtle

Nicknamed the 'Turtle' upon its release in 1976, this watch was in production for 12 years, leading to its abundance in the vintage market. It earned its name due to the case design, which resembles a turtle shell.

Skeleton Bridge

A skeleton bridge describes a bridge in a skeletonised watch movement. Unlike a traditional bridge, which is a solid structure holding the wheels and gears, a skeleton bridge is meticulously hollowed out and decorated to enhance the watch's artistic design.

Skeleton Dial

A skeleton dial features a watch face where the dial and some movement parts are deliberately openworked to reveal the intricate inner workings, including gears, springs, and the balance wheel.

Skeleton Hand

A skeleton hand is a watch hand that has been hollowed out or has sections removed, creating a see-through effect.

Skeleton Movement

A skeleton movement refers to a watch mechanism where all non-essential metal from the bridges and plates is carefully removed to unveil the intricate inner workings of the watch, such as gears, springs, and the balance wheel.

Slim Bezel

A slim bezel is a narrower version of a standard bezel.

Slim Case Back

A slim case back is a narrower version of a standard case back.

Slim Sapphire

A slim sapphire refers to a narrower version of a standard sapphire crystal.

SNK Bezel

The SNK bezel pertains to the bezel on the Seiko 5 SNK series, which is typically a fixed (non-rotating) bezel featuring a classic, pilot-inspired design.

SNK Field Dial

A Seiko "SNK Field Dial" is a military-inspired watch characterised by a highly legible, utilitarian design. It typically features Arabic numerals, a matte dial, luminous hands and markers, and a 24-hour track for military time.

SNZH

The Seiko SNZH53 is a discontinued, affordable automatic watch from the Seiko 5 line, affectionately known as the "Fifty Five Fathoms" due to its design, which pays homage to the Blancpain Fifty Fathoms dive watch.

Solid Case Back

A solid case back on a watch is an opaque metal backing that fully encases the movement. This design provides durability and a traditional aesthetic, often with space for engravings.

Spring Bar

A spring bar is a thin metal rod that contains a spring inside. It fits between the lugs of your watch and secures the strap or bracelet in place. When pressed inward, the ends retract, allowing you to remove or install the strap.

Spring Bar Tool

A spring bar tool is a forked tool designed for safely removing spring bars.

SRP Turtle

The SRP Turtle refers to a popular line of modern Seiko Prospex dive watches. These watches are notable for their reintroduction of the iconic rounded cushion case, which resembles a turtle shell.

SRPD Case

SRPD refers to the Seiko 5 Sports series code for a line of modern dive-style watches that replaced the well-known SKX model.

SRPD Mod

An SRPD mod refers to the practice of modifying a Seiko 5 Sports (SRPD) watch. This can involve changing parts such as the bezel, dial, hands, or crystal to create a unique and personalised timepiece.

SS

SS most commonly stands for "stainless steel," which refers to the material of the watch case. Less frequently, it can refer to a "small second" sub-dial—a separate dial for tracking seconds, particularly in older or more complex mechanical watches.

SS Case

The term SS case specifically refers to a 316L stainless steel case.

SS Crown

SS crown refers to a 316L stainless steel crown.

SS Insert

SS insert refers to a 316L stainless steel insert.

Stem Extractor

A specialised tool used to remove the stem, which is the rod connecting the watch’s crown to its inner movement. This allows the user to wind the watch and set the time.

Submariner

The Submariner is a luxury dive watch line made by Rolex, originally designed for professional divers. Known for its durability, water resistance, and iconic design, the watch was introduced in 1953 and was one of the first to offer 100 meters of water resistance. Today, it is recognised as a cultural icon, worn by individuals beyond the diving community.

Sumo

The Sumo is a popular Prospex dive watch characterised by its muscular, 45mm case and robust construction. The nickname "Sumo" likely derives from its powerful appearance or the resemblance of the 12 o'clock marker to sumo wrestling gear.

Sunburst Dial

A sunburst dial features a radial brushed finish that creates a shimmering effect by reflecting light from the centre outward. This texture is achieved through a specialised brushing technique that etches fine lines radiating from the centre, often finished with a transparent lacquer that preserves the pattern.

Sunray Finish

A sunray finish is a decorative brushing technique that produces fine lines radiating from the centre of a component, such as a watch dial, resembling sunrays.

Super-LumiNova

Super-LumiNova is a non-radioactive, photoluminescent pigment used in watches to make the hands, hour markers, and other dial elements glow in the dark. It absorbs light energy and re-emits it over time.

Sword Hands

Sword hands are time indicators shaped like a sword blade. They are wide at the base and taper to a sharp point, providing a classic look and excellent legibility. This design, known as "Glaive" in French, often features a central ridge or a larger surface area for luminescent material.

Tachymeter Bezel

A tachymeter bezel is a fixed scale on a chronograph watch, used to measure speed or distance by converting elapsed time into units per hour.

Tapisserie

Tapisserie is a guilloché technique similar to Clous de Paris, resulting in miniature pyramid-like squares that primarily decorate a watch dial.

Tension Ring

A tension ring is a gasket that is under tension, meaning it is stretched or compressed to create a seal, especially around the crystal. This is sometimes referred to as a "tension ring crystal."

Thread Crown

A threaded crown is a screw-down crown featuring threads that allow it to be tightly screwed into the watch case, creating a watertight seal.

Thread Gasket

A thread gasket is a ring-shaped seal made of rubber, silicone, or other materials, designed to create a watertight and airtight seal at points where a threaded component meets the watch case, such as the crown or case back.

Threaded Stem

A threaded stem is the rod connecting the crown (the external knob) to the movement. It includes a threaded section designed to screw into the crown, enhancing water resistance.

Timing Bezel

A timing bezel is a rotating outer ring on a watch, marked for measuring elapsed time.

Tool Kit

A tool kit consists of a set of specialized tools used for watch maintenance and repair.

Tool Watch

A tool watch is a timepiece designed primarily for durability, reliability, and functionality in demanding environments or for specific tasks, rather than focusing solely on aesthetics.

Top Hat Crystal

A Top Hat crystal in watches refers to a type of crystal that is thicker than the watch case and extends above the bezel. This design typically features a flat top and either straight or rounded sides. It gives the watch a vintage appearance reminiscent of older dive watches and creates a distinctive profile by reflecting light in an intriguing way, sometimes appearing as a "glowing ring" from the side.

Tropical Dial

A tropical dial is a vintage watch dial that has developed a unique patina over time due to exposure to sunlight, humidity, and heat. The most common effect is the fading of a black dial into various shades of brown, orange, or caramel, although other colors can also change.

Tropical Strap

A tropical strap is a type of rubber watch strap originally designed for dive watches in the 1960s, known for its durability and water resistance.

Tuna

"Tuna" is a popular nickname for a series of rugged, professional dive watches produced by Seiko. The name derives from the watch's distinctive cylindrical, lugless case with a protective outer shroud, resembling a tuna can.

Tweezers

Tweezers used in watchmaking are typically small and possess extremely sharp points for picking up watch components and moving parts around. The smallest pointed tweezers are designed specifically for positioning watch parts without bending or shaping them.

Unidirectional Bezel

A unidirectional bezel is a rotating bezel on a watch that can only turn in one direction, most often counterclockwise for diver watches. This feature enhances safety by preventing accidental adjustments that could lead to miscalculating elapsed time, which can be critical underwater.

Vintage

A vintage watch is generally defined as a timepiece that is at least 20 to 25 years old, although there is no strict, universal definition.

Vintage Compressor

A vintage Compressor watch is a dive watch with a unique case design developed by Ervin Piquerez S.A. (EPSA) that utilizes external water pressure to enhance its water resistance.

Vintage Hardlex

Vintage Hardlex refers to the proprietary mineral glass crystal developed by Seiko in the 1960s and used in many of its watch models, including vintage ones.

VK31 Quartz

VK31 is a "mechaquartz" movement produced by Seiko Instruments (SII), known for its "sweep second" function, which provides a smooth, mechanical-like motion to the second hand instead of the typical ticking seen in standard quartz watches.

VK61 Chrono

VK61 is a mecha-quartz chronograph movement made by Seiko Instruments (TMI), combining the accuracy of quartz technology with the feel of a mechanical chronograph.

VK63 Movement

The VK63 is a mecha-quartz chronograph movement from Seiko Instruments Inc. (SII) that combines the precision of quartz timekeeping with a mechanical module for the chronograph functions.

VK64 Movement

The VK64 is a meca-quartz hybrid movement in watches, merging the accuracy of a quartz movement with the mechanical feel and functionality of a traditional chronograph.

VK64 Pusher

The VK64 pusher refers to the push-button on a watch equipped with a Seiko VK64 meca-quartz movement, used to control the chronograph functions.

Water Resistance

Water resistance in watches measures how well a timepiece is sealed against water intrusion, typically indicated by pressure ratings like BAR, ATM, or meters.

Water Resistance Test

A water resistance test for a watch assesses its ability to withstand pressure in water, rather than determining how deep it can go.

Winding Stem

The winding stem is the metal shaft that connects the external crown to the internal movement of a watch. It is used to wind the mainspring and set the time and date.

Yacht Bezel

A Yacht bezel is a rotating, bidirectional bezel on a watch, most notably featured on the Rolex Yacht-Master. It allows users to track time intervals for activities like timing a sailing race or maneuvering in a harbor.

Yacht-Master

The Yacht-Master is a luxurious sports watch released by Rolex in 1992. It combines functionality for yachting and sailing with high-end materials and design. Key features include a bidirectional rotating bezel for measuring elapsed time and a water resistance rating of 100 meters, making it a versatile instrument that transitions effortlessly from sea to land.

Zulu Straps

A Zulu strap is a durable, one-piece watch strap typically made of thick nylon with heavy-duty, rounded hardware. Designed for robustness and reliability, it is an evolution of the NATO strap, often thicker and featuring more substantial metal loops and a buckle, making it ideal for rugged conditions, though it may lack the extra flap found on certain NATO models.

Seiko Modding FAQ

What is the best movement for a beginner Seiko mod?

The NH35 is the gold standard for beginners. It offers hacking seconds, hand-winding, 41-hour power reserve, and is compatible with nearly all SKX, SRPD, and 5KX cases. It’s reliable, affordable (~$35), and has a massive aftermarket parts ecosystem.

Should I upgrade to AR sapphire or keep Hardlex?

Upgrade to double-domed AR sapphire for scratch resistance and clarity. Hardlex is impact-resistant but scratches easily. Use AR Neutral coating for photography or Blue AR for that classic Seiko flare.

What’s the difference between 120-click and 150-click bezels?

120-click = 0.5° steps (standard diver precision). 150-click = 0.4° steps (2025 premium upgrade for ultra-smooth action). Both are unidirectional. Pair with a ceramic insert for longevity.

Can I swap a 7S26 movement for an NH35?

Yes, but you’ll need a conversion case or NH35-compatible dial (check dial feet at 6H3H). The 7S26 lacks hacking and hand-winding. Use a stem extender if the crown sits too far back.

What’s the best case material in 2025?

904L steel is the premium choice (36% more corrosion-resistant than 316L). For budget builds, 316L is marine-grade and sufficient. Avoid brass unless you want intentional patina.

How do I achieve 200m water resistance?

Use screw-down crown, case gasket kit, bezel gasket, and double AR sapphire with compression ring. Test with a 15 ATM vacuum tester. Never skip the case back gasket.

What lume lasts the longest?

BGW9 (Blue Lume) glows for 12+ hours. C3 Super-LumiNova is brighter initially but fades faster (~8 hours). Apply with a lume syringe and charge under UV for max brightness.

Is modding a Seiko legal?

Yes for personal use. Avoid selling watches with trademarked logos (e.g., Rolex coronet). Use homage terms, not brand names. 2025 platforms like Etsy require “no logo” disclaimers.

What’s the ideal wrist size for a 40mm case?

6.5–7.5 inches is perfect. Lug-to-lug should be under 48mm. The 40mm case is the “Goldilocks” size for SKX, Turtle, and 5KX mods. Go 38mm for smaller wrists, 42mm+ for bold looks.