WatchAdvisor understands that a proper education is the foundation for understanding the “complicated” world of fine watches. Even a basic fine watch contains over 100 working parts. These incredibly small parts are all designed to fit together to make your mechanical watch «tick tack».
Even the smallest parts of the watch serve a purpose and help the watch to work continuously over the years. The following list features many of the basic terms relating to the parts of a fine watch:
The register, also known as a recorder, is a sub-dial on the face of a chronograph that can record periods of time up to 12 or 24 hours.
30 Minute Register
Similar to the hour register, the 30 minute register is a sub-dial on a chronograph that records periods of time up to 30 minutes.
Also referred to as a day and night indicator, it allows the wearer to determine the time of day on a 12 hour analog or digital watch.
A term describing a clock or watch having hour and minute hands rather than using digital liquid crystal display (LCD).
Is an accurate yearly calendar that must be adjusted at the end of February. The watch will display the day, date and month, typically including the year. Read about different types of calendar complications.
Is a watch that uses certain alloys in parts of the watch including the escape and balance wheel. This allows the watch to be unaffected by a magnetic field and not lose time. Simple items such as a TV, cell phone or stereo can cause enough magnetism to counteract the balance, preventing the watch to keep time accurately.
The small window that is either carved or cut into the dial to display various indications, including the date.
A unit of pressure for the standard atmospheric pressure at sea level. One atmosphere is the pressure of 1kg/cm2 and corresponds to 10 meters of depth. An ATM is displayed as a value such as 5ATM.
Is a type of mechanical watch. It winds with the movement of the wearer’s wrist by a small weight rotating with the motion. Automatic watches can also be manually wound by turning the crown. Learn more about automatic movements.
An extra dial for information, also referred to as a subdial, different information is displayed depending on the complication. Watches can have as many as four auxiliary dials, typically found on chronographs, alarm watches or dual time zones but not restricted to these style watches.
Also called the hairspring; the spring governing the balance wheel. It coils and recoils to swing the balance wheel to regulate time.
A device which regularizes the movement to regulate time equally in a watch or clock. This works the same way a pendulum works.
The strap that wraps around your wrist to keep the watch in position. Typically referring to a leather or rubber band, often called a strap.
Battery Reserve Indicator
The end-of-life indicator on a quartz watch. Typically the second hand will jump in two to four second intervals.
Another unit of measurement relating to the pressure a watch can withstand. One bar is about equal to the atmospheric pressure at sea level and is approximately 10 meters.
The drum-shaped container that houses the mainspring in a mechanical watch. The size of the barrel directly corresponds to how long the power reserve will hold. A double barrel will increase the power reserve.
A filed, turned or obliquely ground surface made to avoid a sharp edge.
The rim that surrounds the dial (face) and retains the crystal. Often made of precious metals, or unique materials. A bezel can be used to measure speed, distance or elapsed time.
Bi-Directional Rotating Bezel
The type of bezel used to track elapsed time. They can be turned clockwise or anti-clockwise.
Metal part in which at least one of the pivots of the moving parts of a watch usually turns. A bridge is strictly a bar with two supports. A bar is fixed to the bottom plate by steady-pins. Bars are generally named after the parts they support e.g. barrel-bar, center-wheel bar, etc.
Precious stone, polished but uncut. In French, the word is also used for an embossed ornament on a dial, and of a fancy gilt nail or stud as used by upholsterers. Typically found set in the crown of a watch.
A complication showing the date and the month. It often shows the day of the week and the year depending on the complexity of the movement.
The term identifying movements from their architecture, origin, reference and maker. It is part of the movement identifying the position and size of the wheel train.
Container that protects the watch movement from dust, moisture and shocks, often referred to as the body of the watch. It gives the watch as attractive an appearance as possible, subject to fashion and the taste of the public and is created out of different materials and precious metals.
The reverse side of the watch case, laying flat on your wrist. Some watches feature an exhibition caseback that is transparent allowing you to see the movement. Casebacks typically carry some engraving noting the name, water resistance and other details.
A bell like sound made when a clock strikes on the hour, half hour, quarter hour and minutes. The chime is similar to that found in a grandfather clock.
A chronograph is a watch that does not only indicate the time of the day in hours, minutes and seconds, but is also equipped with an additional mechanism – operated manually by push buttons –which makes possible to measure continuous or discontinuous intervals of time, from a fraction of a second to 12 hours.
A precision watch, finely set and tested in various positions and temperatures, for which an official certificate has been issued. The test is preformed by the official Swiss testing laboratory called the Controle Officiel Suisse des Chronometeres (COSC) and watches go through a rigorous 15 day test.
A multi-part mechanism providing an additional horological function, providing more information than just the time. Complicated functions include minute repeater, tourbillon, perpetual calendar, split second chronograph and others.
Invented by Rolex, it is similar to a chronograph except for the fact that the tachymeter is on the bezel rather than the outer rim of the dial.
Device with which to wind the watch. Can be a screw down version or pull-out. Crowns are also used to set the time and the calendar.
The clear cover protecting the dial from dust and damage. A crystal is typically made of glass, acrylic, mineral or sapphire.
A small magnified lens found on the crystal that is located above the date to make it easier to read.
The art of producing a design, pattern or wavy appearance on a metal.
A complication showing both the date and the day of the week.
Typically found in dual time zone watches, see also AM/PM Indicator. A colored band that shows which zone is daytime and which is night time.
A type of buckle that hinges closed. Expands to slide over your wrist when opened.
Found on many diving watches, this alarm sounds or vibrates when the diver passes a preset depth.
Indicating the face of the watch. The dial holds various markings to show the hours, minutes and seconds or more depending on the complications of the watch. Dials vary much in shape, decoration, material, etc. The indicators are given by means of numerals, divisions or symbols of various types.
Developed in the 1970s, digital watches use arabic numbers in an LCD display.
Measures both current local time and at least one other time zone. It can be found in a twin dial, extra hand or subdial. Also referred to as world time.
Elapsed Time Rotating Bezel
Graduated rotating bezel to keep track of periods of time. Elapsed time can be read off of the bezel rather than needing to subtract time if using a regular dial.
Substance composed of siliceous sand to which oxides are added to give a very wide range of colors suitable for the decoration of metallic surfaces, especially gold, silver or copper. When fired, enamel adheres to the metal and acquires the consistency of glass.
Engraving a watch case with a repetitive design by antique machines. This can be done on the dial, case, bezel or movements. Also referred to as “Guilloche”
Equation of Time
A complication showing true solar time in nature and mean solar time in man. There are only four days per year where the day is exactly 24-hours long. On every other day, the days are slightly shorter or longer depending on the position of the Earth.
The last wheel in a going train; works with the fork or lever and escapes one pulse at a time.
Mechanism fitted between the train and the regulating organ of most timepieces. The purpose of the escapement is to maintain the oscillations of the regulating organ. The escapement is one of the most important parts of any watch.
In a split-seconds chronograph, a second center seconds hand that can move while remaining superimposed on the first hand, but can be stopped and brought back to zero together with the first hand as it moves. It can also be stopped and brought back to zero together with the first hand and is useful to aviators
The number of vibrations, oscillations, per second, in hertz (Hz).
A small ring to create an air-tight seal around the caseback, crystal and crown. It protects against water during normal wear. Gaskets are rubber and should be checked every few years to maintain water resistance.
A system of gears the transfers power from the mainspring to the escapement.
The quality seal awarded by an independent bureau in Geneva. Companies submit movements to this bureau for testing. They are tested against 12 different criteria related to the quality of the movement, including the finishing and materials. Movements must also be manufactured in Geneva. The Geneva coat of arms is stamped onto the movement.
Also known as Greenwich Mean Time, it is the international standard of time that the world is set to. Every time zone is set against GMT. In watches, a GMT reference refers to the ability to show dual time zones with a second hour hand, primarily found in a 24-hour mode to determine day from night.
A watch or clock that strikes the hour, quarter hours and minutes when the wearer pushes the button; a Petite Sonnerie strikes at the hour only.
Extremely varied pattern of crossing or interlaced lines, giving a decorative effect. It is an especially complicated mechanical engraving technique.
The very fine spring, no thicker than a strand of hair, that vibrates the balance wheel and causes it to recoil. Also called a balance spring.
Helium Escape Valve
Found on diving watches for deep sea-expeditions. The valve is used to release water pressure found at deep levels to avoid damaging the watch or popping the crystal.
The science, craft, industry and trade concerned with instruments for measuring time.
An hour indicator on an analog watch. Used in place or alongside numerals.
A bearing made of a ruby or other type jewel or synthetic gemstone; the four types of jewels include: cap jewel, hole jewel, roller jewel or ruby pin, pallet jewel or stone. Used to reduce friction in the movement of mechanical watches.
The Karat, like all jewelry, is an indication showing the purity of metal, such as gold, representing the purity. In gold, 24k is pure, while 18k is 18 parts pure and 6 parts other metal.
A vegetable product, the resin of certain trees found in the Far East (China, Japan), which gives a fine black or red color. The term may also be used to denote articles made of several layers of hardened lacquer.
Part of the movement that divides into two pallets that lock and unlock the escape wheel teeth.
A watch manufactured in a specific amount, typically numbered and available in limited quantities. These watches are highly sought after.
Liquid Crystal Display
Also known as LCD, it is another term for digital watches, showing an arabic numeral display. The liquid is encased between two clear plates and activated by electronic impulses.
Luminous (lume) markers and hands are made by applying glow in the dark coating to the indicator. This allows them to illuminate automatically in a darkened environment.
Curved attachment of the watch case to attach the bracelet, strap or band.
A flat spring coiled or wound to supply power to the watch.
The part of the watch that prevents the barrel from being over wound, not found in all models.
A watch wound daily by winding the crown to tighten the spring. Most manual wind watches hold time for 36-48 hours before needing to be rewound. Learn more about manual wind watches.
An accurate timepiece typically found on a ship. These are used for determining the longitude. Found in a box that is mounted to keep in a horizontal position to maintain precision.
Mechanical watches are the most traditional type of watch. They usually consist of about 120-180 individual parts. This is a watch that runs without any electrical source and can consist of manual wind watches or automatic watches.
The most common unit of measurement when referring to the water resistance of a watch. Relates to how deep a watch is able to go, testing is done in a controlled laboratory.
Far more scratch-resistant than synthetic glass. Hardness level 5.
A timepiece that can be made to strike the time in hours, quarters and minutes, by means of a push piece or slide.
A type of chronograph that is started using a single button rather than multiple.
Mother of Pearl
Interior shell that is thinly sliced and used as a watch dial. Most are found with a white luster but can be found in gray, blue, pink and salmon tones.
The fully functioning assembly of all the main timekeeping organs of a watch. Three main movements include mechanical, automatic and quartz.
Including both Roman (I, II, III, IV, etc) and Arabic (1,2,3,4, etc) numbers to mark the hours around the dial.
The regular movement of a body, such as balance wheel or pendulum, between two points from one extreme to the other and back again. Anything with a regular oscillation can be used to keep time.
A number of jewels or stones set close together, typically found in the dial or case.
A calendar complication capable of showing the day, date and month but often includes the moon phase and year. It takes into account short and long months in addition to the leap year. It is accurate until the year 2100.
Physical Vapor Deposition
Also known as PVD. This is a type of coating applied to a watch case or bracelet to finish the watch.
A metal plate that supports the bridges and various parts of the movement.
One of the rarest and most durable metals used in watch cases. Platinum does not tarnish and keeps the watch looking like new.
Used to make the case and bracelet smooth and brilliant by very fine-grained abrasives or by rubbing with a burnisher.
Running time in excess of the normal time (24 hours for ordinary watches) between two consecutive windings. In an ordinary watch, the power reserve usually provides for 10 to 16 hours running. Some watches feature a Power Reserve Indicator to alert the wearer of time remaining until the watch stops. Can also be referred to as the Reserve de Marche.
Quartz watches are battery powered. They can either have hands, like the more traditional mechanical watch, or have a digital display. These watches are much more accurate than even the most expensive manual wind watches. Learn more about the quartz movement and the quartz revolution.
The part of an automatic watch that rotates as it is worn to wind the main spring.
Scratch-resistant glass with a hardness of 9 used in many watch crystals or exhibition case backs.. The only harder substance is diamond.
Screw Down Crown
A crown that is threaded and tightened when the wearer screws it in. It utilizes a gasket to make the watch water tight.
Second Time Zone Indicator
Found on an additional dial, used to set a separate time zone to be viewed simultaneously as the local time.
Used in a watch whose movement is protected against shocks, i.e. fitted with a shock-absorber system. Defined by the US government as the ability to withstand an impact of being dropped onto a wood floor from a height of 3 feet.
The time of rotation of the Earth as measured from the stars. About 3 minutes, 56 seconds shorter than the mean solar day.
A watch with a mechanism reduced to the minimum material by punching, sawing and milling. Built in between the transparent dial and glass bottom, they create attractive, decorative watches and allow the wearer to view the movement.
A second hand on the second spring. Can be stopped independently of the switched-on chronograph and return to the current time with the push of a button.
Spring Bar / Spring Pins
Spring loaded pins located between the lugs to attach the bracelet or strap.
An instrument that only measures intervals of time and does not indicate the time of day. Another word for a chronograph.
Also referred to as a sub dial, it is an auxiliary dial on the face of the watch. This can be used for various functions including the seconds hand and chronograph functions.
An additional complication found on watches, it is a wheel that is partially visible through the dial indicating the sun and moon in a 24-hour period.
A watch is considered Swiss-made if its movement is assembled, started, adjusted and controlled by the manufacturer in Switzerland. At least 50% of the value of all the components (not counting the cost of assembly) are Swiss-made and are subject to technical control in Switzerland according to the applicable system.
A mark identifying the watch was assembled in Switzerland with Swiss-made components.
A tachymeter (also known as tachometer) measures the speed at which the wearer has traveled over the measured distance found commonly on a chronograph. The wearer starts the chronograph when passing the starting point and stops it when passing the finish. The wearer can then read the speed in units per hour off the tachymeter scale.
One of the most common strap closures found. A traditional loop and pin that resembles a belt buckle.
Designed by Cartier, it is a rectangular watch with bars along the sides the resemble the tracks of a tank used in World War I.
A telemeter determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. Like a tachymeter, it consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch dial. One application of a telemeter would be determining the distance of a storm from its observer. The wearer starts the chronograph at the instant the flash of lighting is seen, then stops it when thunder is heard. A reading can then be taken to determine the distance of the storm from the observer in miles on the telemeter scale.
Totaliser / Totalizer
A mechanism used to track elapsed time, typically found in a subdial.
A device invented by A.L. Breguet in 1801 to eliminate errors of rate in the vertical positions. It consists of a mobile carriage or cage carrying all the parts of the escapement, with the balance in the center. It is designed to avoid any errors that may be caused by a change in the wearers wrist position. Tourbillons typically rotate one per minute.
Uni-Directional Rotating Bezel
Typically found on divers’ watches. The bezel only rotates in a counterclockwise direction and is designed to prevent a diver from running out of air by over estimating remaining air supply.
Mean solar time for the Greenwich meridian, but counted from noon to noon.
The movement of an oscillating part of the watch, limited by two extreme positions. Generally 5 or 6 vibrations per second, 18,000 or 21,600 per hour, but can also be a higher frequency with as many as seven or ten vibrations, 25,200 or 36,000 per hour. See also: Frequency.
The case, crown, push button and glass of a water-resistant watch are made in such a way that no dust or water can penetrate. Watches undergo in-house tests in a laboratory under controlled conditions. Learn more about water resistance markings.
A prohibited term used when describing the water resistance of a watch. No watch is 100% waterproof.
Another word used for the crown. A button found on the side of the case used to wind the mainspring.
World Time Complication
A dial that contains up to 24 different time zones, found usually on the outer edge of a dial. The time zones are represented by using the names of major cities.
A countdown timer used to sound warning signals during a race, originally developed for the countdown to a boat race.