Acrylic Crystal
A lightweight and resilient type of watch face cover, crafted from acrylic plastic, which offers superior resistance to shattering.

Alarm
A watch functionality that triggers a sound alert at a specific, user-set time.

Alarm Repeater
An intricate horological feature that not only sounds a one-time alert but also continues to chime at regular intervals.

Amplitude
The angle, measured in degrees, of the balance wheel's swing during a single vibration, with a full oscillation comprising two vibrations. An increase in friction can cause a reduction in amplitude.

Analog
A traditional watch design that indicates the time with moving hands on a numbered dial.

Anti-Magnetic
A watch engineered to withstand the disruptive influence of magnetic fields on its mechanical timekeeping mechanism.

Anti-Reflective Coating
A special layer applied to the surface of watch crystals to minimize glare and enhance legibility.

Annual Calendar
A watch feature that presents the day, date, and month, and requires manual adjustment only once annually, typically after February.

Arabic Numerals
Numerical hour indicators on a watch dial that are represented by characters from the Arabic numeral system (1, 2, 3, etc.).

Automatic Movement
A self-winding watch mechanism that harnesses the motion of the wearer's wrist to power the mainspring, thereby negating the necessity for manual winding.

Balance Wheel   
The part of a mechanical watch movement that oscillates, dividing time into equal segments. This is the regulating organ that (along with the hairspring) controls the watch’s timekeeping accuracy. 

Bar  
A unit of pressure used to measure a watch's water resistance, with one bar equal to approximately 10 meters of water resistance.

Barrel  
The part of a watch movement that houses the mainspring, which provides the energy to power the watch.

Beat Error 
Measured in milliseconds, this is more or less the centeredness of the roller jewel (plateau) in relation to the escapement. 0.0ms is perfect symmetry of the balance and escapement. This is an adjustable figure that the watchmaker determines when adjusting the watch during production or servicing.

Bezel 
The ring-shaped part on the front of a watch that surrounds the crystal and can be rotated on some watches to perform various functions, such as tracking elapsed time. 

Bi-Compax     
A type of chronograph with two subdials, typically used for measuring elapsed time.

Butterfly Clasp 
It consists of two metal hinges that open to the right and left – just like a butterfly spreading its wings. Some butterfly clasps are available with push button release.

Caliber
A designation for the specific model or type of a watch's movement, often serving as a shorthand reference to the watch's design and mechanics.

Cambered
A descriptor for a watch crystal or case back that exhibits a gracefully arched profile.

Casing
The meticulous process of integrating the movement within the protective enclosure of the watch case.

Ceramic
A robust, scratch-resistant material used in the crafting of luxury sports timepieces for its durability and aesthetic appeal.

Chronograph
A sophisticated timepiece feature enabling the measurement of elapsed time, typically equipped with additional subdials and side pushers for operation.

Chronometer
A timepiece distinguished by its certification from an authoritative body for meeting stringent standards in precision, including water and shock resistance, and anti-magnetism.

COSC
The Contrôle Officiel Suisse des Chronomètres, the esteemed Swiss institution that certifies the precision and performance of wristwatch movements, authorizing them to bear the title of chronometers.

Clasp
The intricate fastening device employed to securely affix a watch band or bracelet around the wearer's wrist.

Co-Axial Escapement
An escapement mechanism pioneered by horologist George Daniels, notable for its reduced friction and heightened timekeeping precision, with exclusive utilization by Omega and Roger W. Smith.

Compax
A chronograph variant with dedicated subdials for hours, minutes, and seconds, originally popularized by the Universal Genève Compax.

Complication
An advanced watch function that extends beyond mere time display, encompassing additional features like date indication, lunar phase tracking, or stopwatch capabilities.

Counterfeit
An illicit imitation designed to replicate a legitimate timepiece, intended to mislead consumers and violate the original manufacturer's intellectual property.

Côtes de Genève
An intricate ornamental finish manifested as a series of linear stripes, applied to movements and various watch components for enhanced visual texture.

Crown
The external knob positioned on the watch case, utilized for time adjustments and potentially for manual winding of the movement.

Crystal
The clear protective barrier mounted above the watch face, crafted from materials such as sapphire, mineral glass, or acrylic for optimal clarity and protection.

Crystal Gasket
A sealant ring, typically composed of rubber or silicone, used to secure the juncture between the case and crystal of a watch, reinforcing its water-resistant properties.

Cyclops Lens
An elevated magnifying element affixed to the watch's crystal, principally designed to enhance the legibility of the date function.

Date Window  
A small window on the watch dial that displays the current date.

Day/Date  
A watch function that displays both the day of the week and the date, often located on the dial or in an aperture.

Delta  
The difference between the greatest value and the least greatest value. In regards to rate, this is the difference between the fastest and slowest positions, measured in seconds. The importance of testing a mechanical watch in 5 positions is reflected by the delta. A watch can be +/- 0 seconds per day in any given position but +/- 20 seconds in another position. At Wristcheck, we value transparency and believe that 5-position results should be displayed for each and every watch.

Deployment Clasp  
A type of watch band closure that folds and locks to secure the watch.

Depth Gauge  
A watch function that can measure the depth of water, typically using a pressure-sensitive membrane.

Diamond-Like Carbon (DLC)  
A hard, wear-resistant coating used on watch cases and other components.

Dial  
The face of the watch that displays the time and other features, often featuring hour markers, subdials, and other design elements.

Digital Watch  
A watch that displays time using digits rather than hands.

Display case back  
A type of watch case back that is transparent, allowing the wearer to see the movement inside the watch.

Diver’s Watch  
A watch that has been specifically designed for use while diving, featuring water-resistant construction, legible dials, and other features necessary for underwater use.

Division  
The division is the distance between each hand and the levelness of the hands. The distance between each hand must be equal, and all hands must be level. 

DM (see also ‘Qualifiers’)  
"Display marks." Watches often have a shelf-life of months or years at the authorized dealer. The watches will accumulate marks from being affixed and removed from displays.  

Double barrel  
A watch movement that features two mainspring barrels, providing increased power reserve and more consistent timekeeping accuracy.

Double Chronograph  
A type of chronograph with two central chronograph hands that can be stopped independently, allowing the timing of two separate events.

Dress Watch  
A type of watch designed to be worn with formal attire, usually with a simple, understated design.

DT (see also ‘Qualifiers’)  
"Date tolerance." The date-jump is outside of the realm of perfection.

Dual Time  
A watch that displays time in two time zones simultaneously, and are independently adjustable.

Ebauche

A partially completed watch movement that is sold to other watchmakers for finishing and assembly.

Enamel Dial
A watch dial that is coated with a layer of enamel, often used for its durability and ability to create intricate designs.

Escapement

A component in a watch movement that helps regulate the timekeeping accuracy by controlling the release of energy from the mainspring. It is a critical component of the watch.

Escape wheel

The wheel is a watch movement that drives the pallet fork of the escapement, providing the impulses that keep the balance wheel oscillating.

Exhibition Caseback
A transparent caseback that allows the wearer to see the watch's movement inside.

Flyback Chronograph  
A type of chronograph function that allows the user to stop, reset, and restart the chronograph with a single button press, rather than multiple presses.

Flywheel   
A rotating disc that provides a visual indication of a watch's winding or power reserve.

Frequency 
The rate at which a watch movement oscillates, measured in hertz or beats per hour, and directly affects the timekeeping accuracy of the watch.

F (see also ‘Qualifiers’) 
"Function." The watch has a functional error that does not effect the value of the watch. This may be something that can be repaired, for example a chronograph hand that returns to zero slower than it should. 

Fusee   
A cone-shaped component used in traditional mechanical watches to regulate the power delivered to the movement.

Gasket 
A rubber, neoprene or plastic ring used to seal the gaps between the case and the case back, crystal and crown to prevent water or dust from entering the case and damaging the movement inside.

Gear Train 
The system of gears which transmits power from the mainspring of the watch to the escapement.

Geneva Seal 
A certification mark applied to watch movements made in the Canton of Geneva, Switzerland, indicating that the movement meets strict quality standards.

Geneva Stripes 
A decorative finishing technique used on watch movements to create a striped pattern, known as Côtes de Genève.

GMT  
A watch that displays a second time zone, usually indicated by an additional central hour hand.

Graining 
A decorative finishing technique used to create a linear pattern on metal watch parts.

Guilloché 
A decorative finishing technique used on watch dials that creates a pattern of intricate lines or curves.

Hack Movement 
A feature that stops the second hand when the hands are being set, used for precision time setting.

Hairspring 
The thin spiral spring in a watch movement that regulates the oscillation of the balance wheel.

Hand-wound 
Referring to a mechanical watch that doesn’t automatically wind. Hand-wound watches are powered by manually turning the crown to wind up the mainspring.

Haute Horlogerie 
Directly translated to “high watchmaking’, Haute Horlogerie is a term used to describe the pinnacle levels of watchmaking, often characterized by complicated movements and decorative finishing techniques. 

Helium Escape Valve 
Found on some advanced diver’s watches and only useful to saturation divers who spend time in pressurised, helium-rich environments. Helium particles are smaller than air and can penetrate a watch case during compression dives. During decompression, these particles expand and could damage a watch unless released through a helium escape valve. Some of these valves are automatic; some have to be operated manually.

HM (see also ‘Qualifiers’) 
"Handling marks." This qualifier acknowledges the presence of very insignificant marks that were created when the watch was handled by the authorized dealer or original owner but the watch is still defined as "unworn." 

Horology 
The study of time and the measurement of time.

Incabloc 
A shock-absorbing system used in watch movements to protect delicate parts from damage due to shock and vibration.

Index
An index on a watch dial refers to the markers that indicate the hours. Instead of numerals, indices can be lines, dots, or shapes.

In-house Movement 
A watch movement that is designed, developed, and manufactured by the same company that produces the watch.

Jeweled Escapement
An escapement that uses synthetic rubies or other gemstones as bearings to reduce friction and wear.

Jewels
Synthetic rubies or sapphires used as bearings in a watch movement to reduce friction.

Jeweler's Loupe
A magnifying tool used to inspect watch components.

Jubilee Bracelet
A type of watch bracelet with five links, developed by Rolex and known for its comfort and durability.

Jump Hour
A watch function that displays the hours using a digital or analog display that "jumps" at the top of each hour.

Karat
In relation to watches, "karat" is a term that refers to the purity of gold used in the watch case, bracelet, or other components. Pure gold is 24 karat, and the number of karats in a piece indicates the amount of gold present in the alloy. For example, an 18-karat gold watch case would consist of 75% pure gold mixed with other metals for added strength.

Lugs
The case extensions that hold a strap or bracelet in place.
Lume
A material applied to watch hands, indices, and dials to make them visible in low-light conditions.

MD (see also ‘Qualifiers’) 
"Manufacturer defects." There are one or more defects present that were caused during the manufacturing or assembly phase.

Mechanical Watch 
A watch with a traditional movement powered not by electronics, but by a mainspring that requires regular winding and is governed by a series of gears and regulating organs.

Minute repeater 
The minute repeater is used to audibly describe the time before the advent of electricity.

Modern 
A modern watch is less than 20 years old.

Moonphase 
A watch with a display showing the phases of the moon during its 29.5-day cycle.

Moonwatch 
A nickname for the Omega Speedmaster Professional, a watch that has been worn by astronauts on NASA space missions.

Mother-of-Pearl 
A material made from the iridescent inner layer of certain mollusk shells, often used for watch dials.

Movement 
The mechanism that powers a watch and keeps time, consisting of the mainspring, balance wheel, and other components.

NATO Strap
A type of nylon watch strap with a distinctive design that originated with military watches.

Nivarox
A type of alloy used to make hairsprings and mainsprings in mechanical watch movements, prized for its stability and durability.

Off-Center Dial
A watch dial that is not located at the center of the watch face, often used for artistic or design reasons.

OCH (see also ‘Qualifiers’)
"Off-centre hands." The hands are slightly misaligned outside of the realm of perfection.

Open-Heart
A watch design that features a cutaway in the dial or caseback to reveal the balance wheel.

OX (see also ‘Qualifiers’)
"Oxidation." There is oxidation present.

Oyster Case
A type of watch case designed by Rolex that is water-resistant and screw-down, typically made of stainless steel.

Perlage 
A decorative finishing technique used to create a circular pattern on metal watch parts.

Perpetual Calendar 
A complication showing the date, day, month & leap year cycle at the minimum. Many will also display the year & Moonphase. This watch will correctly adjust for short and long months as well as 28 days of February once in 4 years.

Power reserve 
The power reserve is the amount of time it takes the movement to run out of energy after it has been fully wound, without being rewound by hand or body movements.

Power Reserve Indicator 
A watch function that displays the remaining power reserve using a hand or subdial.

Pusher 
The buttons on a chronograph that start, stop, and reset the timing functions.

PVD Coating 
A coating process used to improve the durability and aesthetics of watch components.

Qualifier
A "qualified" watch is a watch that meets all the criteria for a particular grade but fails the standard in one area. These are used only for watches that are designated as "unworn" 10 but acknowledge imperfections. Qualifiers are only used for grading modern watches. These are very insignificant and do not affect the total score but are necessary to make it clear that we consign "pre-owned" watches that even when unworn can sometimes show signs of imperfections.

Quartz-movement
A quartz watch is a battery-powered watch. The battery sends an electric signal via a microchip circuit to a small quartz crystal that then vibrates at a precise rate. Those vibrations regulate a stepper motor that moves the watch's hands. 

Radium 
A radioactive material once used to make watch dials glow in the dark, is now replaced by safer alternatives.

Rate 
The amount of seconds gained or lost is measured in seconds per day (s/d).

Rattrapante 
A rattrapante mechanism consists of a single chronograph complication where two hands track the time of two events that start simultaneously but end at different times, also known as split-second chronograph.

Regulateur 
A watch with non-coaxial hands, in other words, with a central minute hand and an hour hand in a separate subdial. The term derives from highly accurate clocks developed by observatories to be used as parent clocks that other timepieces could be set by.

Rehaut 
The inner ring of a watch dial that surrounds the hour markers and features additional markings or engravings.

Repeater 
A complication that chimes the time on demand.

Retrograde 
A lateral or vertical scale is used to display functions such as the time, date, or power reserve. A hand or indicator moves across a retrograde scale and then jumps back to its starting point as appropriate.

Rotating Bezel 
A bezel that can be rotated to measure elapsed time, is typically used in diving or other sports watches.

S (see also ‘Qualifiers’) 
"Stains." There are stains present.

Sapphire Crystal 
A hard, scratch-resistant substance used by most luxury watch brands to cover the dial.

Screw-Down Crown 
A type of crown that screws in to provide extra water resistance.

Shock Resistance 
A watch's ability to withstand shocks and impacts without damage.

Skeleton Watch 
A watch with a see-through dial and/or case that shows the inner workings of the movement.

Slide Rule Bezel 
A type of rotating bezel used in aviation watches that can be used for various calculations such as fuel consumption and speed.

Small Seconds 
A watch function that displays the seconds using a small subdial rather than a central hand.

Smartwatch 
A watch with digital functionality that can connect to a smartphone.

Solar-Powered Watch 
A watch that is powered by a solar cell.

Spring Bar 
The small, spring-loaded bars used to attach watch straps and bracelets to the watch case.

Spring Drive 
A type of watch movement invented by Seiko that combines a mechanical mainspring with electronic regulation for high accuracy.

Subdial 
A smaller dial on the watch face that displays additional information, such as a second time zone, chronograph sub-seconds, or moon phase.

Sunburst Dial 
A type of watch dial with a textured pattern that radiates from the center of the dial.

Super-LumiNova 
A type of luminescent material used on watch dials and hands to make them visible in the dark.

Swiss lever Escapement 
The Swiss lever escapement is a timekeeping mechanism used in mechanical watches, characterized by its reliability and precision, which controls the movement's energy release through interactions between the escapement wheel and a lever with pallets.

Swiss Made 
A designation that indicates a watch was made in Switzerland and meets certain quality standards.

Tachymeter
A bezel or subdial used to measure speed over a fixed distance.

Telemeter
A scale on a watch dial or bezel that can be used to measure distance based on time and speed of sound.

Titanium
A lightweight and durable metal often used in high-end watches for its strength and resistance to corrosion.

Tonneau
A watch case shape that is curved in the horizontal and vertical directions, resembling a barrel.

Tapisserie Dial
The Tapisserie pattern is a signature feature of Audemars Piguet's Royal Oak watches, characterized by a distinctive, textured pattern of fine, interwoven squares created through guilloché engraving. There are three main patterns, all varying in size; Petite Tapisserie, Grande Tapisserie, and Mega Tapisserie.

Tourbillon
A complication that counteracts the effects of gravity on the watch movement.

Tourbillon Cage
The rotating cage that contains the balance wheel, escapement, and other parts in a tourbillon complication.

TR (see also ‘Qualifiers’)
"Timing results." This qualifer acknowledges some aspect of the timing results being outside of the realm of perfection but is not cause for repair.

Train
The series of gears that transmit power from the mainspring to the escapement in a watch movement.

Tritium
A self-illuminating material used to make watch dials and hands visible in the dark.

Tritium Gas Tubes
Small glass tubes filled with tritium gas that emit light and are used to mark the hour indices on some watches.

Uni-Directional Bezel
A bezel that only rotates in one direction to track elapsed time.

Unitas
A Swiss watch movement manufacturer that has produced many popular movements used by other watch brands.

Universal Time
A system that divides the Earth into 24 time zones, with each zone separated by one hour of time difference from its neighbors.

UTC
Coordinated Universal Time, another time standard used by many watch brands for displaying multiple time zones.

Vibration
The back-and-forth motion of the balance wheel in a watch movement, measured in beats per hour (BPH).

Vintage
A vintage watch is 20 years or older. While not a conventional definition, we believe that 20 years is enough time to alter the state of the original watch if it is worn daily.

Water Resistance
The ability of a watch to withstand water pressure and prevent water from entering the case.

Water Resistance Depth Rating
The depth to which a watch can be safely submerged without water entering the case.

Water Resistance Test
A test performed on a watch to determine its level of water resistance, typically using a special testing chamber.

Winding
The process of manually or automatically winding the mainspring of a mechanical watch to provide power to the movement.

World Time
A watch that displays the time in multiple time zones simultaneously.

X-Lume
X-Lume is a term that can be associated with the luminescent coating used on some watch dials and hands to enhance visibility in low-light conditions. It refers to a type of phosphorescent material that, after being charged by light, glows in the dark.

X Series
Some watch manufacturers may use "X Series" to denote a special or experimental collection within their brand, highlighting innovation or a significant departure from their standard line-up.

Yacht Timer (Regatta Timer)
A type of countdown timer used in yacht racing to synchronize the start of the race and regatta race timing.

Zulu Time
Zulu time, also known as Coordinated Universal Time (UTC), is a watch term used to describe the world's time standard. Watches that display Zulu time are often used in aviation and military contexts where synchronized timekeeping is crucial.

24-Hour Dial
A watch dial that displays time using a 24-hour scale instead of a 12-hour scale.

24-Hour Hand
A watch hand that indicates the time using a 24-hour scale instead of a 12-hour scale.

316L Stainless Steel
A type of stainless steel commonly used in watch cases and bracelets for its durability and resistance to corrosion.

904L Stainless Steel
A type of stainless steel produced by Rolex, used in high-end watches for its increased resistance to corrosion and rust.