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Watch Glossary and Terms with Images

watch glossaryWe thought that for timepieces novices would be useful to learn some new terms, watch mechanism secrets and pieces design aspects. So we decided to create this new Watch Glossary. Watch experts will find here interesting information as we are going to update the glossary with new terms regularly. For more pleasure and better understanding our watch glossary fits colorful pictures. If you are going to buy specific timepiece this watch glossary will help you to choose a perfect watch.

Enjoy new knowledge!


Watches can be magnetized when it comes to strong magnetic field and because of that watches wouldn’t show so accurate time. Some watchmakers make their watches anti-magnetic. It can be achieved by using alloy or non-magnetic material for certain parts of the watch.


(in French: montres à guichet)
Small opening in the dial that displays certain information such as date, day, month or moon phase.

Watch Term Image - Aperture

Applique or Applied chapters

Numerals or symbols cut out of a sheet metal and stuck or riveted to the dial.

Watch Term Image - Applique or Applied chapters


I watch terms Arbor is an axle used to rotate or swing the wheels. (eg barrel arbor)

Watch term - barrel arbor


Essential characteristic of any diving watches as atmosphere is a measurement of pressure. It is the amount of air pressure at sea level that a watch can withstand. (1ATM = 1BAR = 10m = 33.3ft).


Process of fitting together the components of a movement. It was formerly done entirely by hand, but the operations have now been largely automated. Nevertheless, the human element is still primordial, especially for inspection and testing.


French term for the parts used for making the three parts of escapement (escape-wheel, lever and roller). Generally, specialist companies supply watchmakers with the lever assortment.

Watch Term Image - Assortiment

Automatic Movement or Automatic Watch

A self-winding watch with mechanical movement. Watches mainspring is wound by the movements or accelerations of the wearer's arm. A rotor (a weight) turns by the motion of your arm and winds the mainspring by transmitting its energy. The energy generated by the movement is transferred into mechanical energy by means of an appropriate mechanism. Then that mechanical energy creates the movement. These watches can be shaken or manually wound if the power reserve runs out. The system was invented in Switzerland by Abraham-Louis Perrelet in the 18th century.

Watch Term Image - Automatic Movement or Automatic Watch


Moving part, usually circular, oscillating about its axis of rotation. The hairspring coupled to it makes it swing to and fro, dividing time into exactly equal parts. Each of the to-and-fro movements of the balance ("tick-tack") is called an "oscillation". One oscillation is composed of two vibrations.



Watch band is a band that holds wristwatches on your hand. Most commonly it’s called as bracelet or strap.

Watch term - bracelet Watch term - strap

Battery reserve indicator

Some watches with batteries have a special feature that shows how much energy is left. A battery reserve on a Quartz watches informs the wearer of low battery. This is often specified by the second hand moving in 2 - 5 second intervals instead of normal 1 second.

Watch term - Battery reserve indicator


A type of watch band made of metal elements of wristwatches that resemble links.

watch bracelet

Bar, lug

In wristwatch-cases, a thin metal rod fixed between the horns, for attaching the wristlet.


Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.
A plain barrel, used in fusee watches, has no teeth. Catgut, then a chain, is coiled round the plain barrel, connecting it to the fusee.

Watch Term Image - Barrel


In a watch movement, the metal rim that secures a jewel.

Watch Term Image - Bazel


The ring around the top of the crystal. Generally holds the glass or crystal in place. A rotating ratchet bezel moves in some watches as part of a complication. Rotating bezels either rotate clockwise, counterclockwise or both to assist in calculations.

Watch Term Image - Bazel


Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame (part of the "ébauche").

Watch Term Image - Bridge

Calendar-watch or Calendar

Watch indicating the date, the month and sometimes the year and the phases of the moon.

Calendar-watch or Calendar


Originally used to mean the size of a watch movement, this term now denotes a type of movement (men's calibre, automatic calibre, etc). When a calibre number is accompanied by the manufacturer's mark, it serves as an indication of origin.



Container that protects the watch-movement from dust, damp and shocks. It also gives the watch as attractive an appearance as possible, subject to fashion and the taste of the public.

Watch Term Image - Case


Bottom of the watch that lies against your skin.

Watch Term Image - Caseback

Casing (up)

Process of inserting and fixing a watch movement into its case.


French term for a watch movement (not including the dial and hands), of which all or part of the components are not assembled.


Watch with two independent time systems: one indicates the time of day, and the other measures brief intervals of time. Counters registering seconds, minutes and even hours can be started and stopped as desired. Also a stopwatch function that uses sub dials to keep track of seconds, minutes and hours.

Watch Term Image - Chronograph


Greek words (chronos + metron) meaning to measure time.

A chronometer is an extremely accurate watch or clock. A Swiss chronometer is a watch, usually mechanical, whose precision has been tested and verified by an official Swiss watch testing bureau COSC. The watch comes with a ratings certificate issued by the institute. The chronometer designation is a badge of honor, proof that the watch is of superior quality.



Any "function" added to a watch, such as a minute repeater, countdown timer, stopwatch, altimeter, asthometer, pulsometer, calendar, moon phase indicator, split second chronograph, power reserve indicator, or alarm.

1. Complications related to timekeeping

a. Acoustical

  • Time signal
  • Alarm
  • Quarter repeater
  • Ten-minute repeater
  • Half-quarter repeater
  • Five-minute repeater
  • Minute repeater
  • Passing hour and half-hour strike
  • Grande sonnerie
  • Petite sonnerie
  • Silencer

b. Silent

  • "A toc" dumb repeater
  • "A tact"

c. Astronomical indications

  • Simple calendar (full or partial)
  • Simple annual calendar (full or partial)
  • "Perpetual" calendar
  • Week number
  • Year
  • Equation of time
  • Sunrise and sunset for a given location
  • Sidereal time
  • Declination of the sun
  • Apparent movement of the planets
  • Line of node
  • Star chart for a given location

d. Measure of short times

  • Independent seconds
  • Chronograph - chronoscope
    • simple
    • with hour and minute totalisers
    • with one scale:
      • tachymetric (speed over a given interval)
      • telemetric (estimated distance based on the speed of sound)
      • asthometric (number of breaths per minute)
      • pulsimetric (number of heartbeats per minute)
    • with multiple scales
    • with split seconds
    • with mono-ratrappante

e. Complications by concept and production (extended definition)

  • Tourbillon
  • Self-winding

f. Complications inspired by everyday life

  • World time
  • Universal time
  • Multiple time zones
  • Regatta dial
  • Diving dial
  • Tide gauge
  • Orienteering dial
  • Fly-back chronograph
  • Power reserve indicator

g. Ultra-complicated watches

2. Complications not related to timekeeping

  • Barometer
  • Compass
  • Altimeter
  • Depth gauge
  • Slide rule

ComplicationWatch Term Image - Complication

Countdown timer

Countdown timer is a watch function that allows wearer keeps track of how much pre-set period of time has been elapsed. Some of them sound a signal a few seconds before time ends up.


Controle Officiel Suisse des Chronometres (Official Swiss Chronometer Testing Institute). They test watches for 15 days and nights at five different positions and temperature ranges. They either pass or fail the watch movement. If the watch passes, it is called a chronometer.

Controle Officiel Suisse des Chronometres


Knob located on the outside of a watch case and used to wind a mechanical watch mainspring. It is also used for setting the right time and for correcting calendar indications.

Watch Term Image - Crown ModernWatch Term Image - Crown Classic


Crystal is a transparent cover used for watch dials. There are 3 main types of crystal used in watches: acrylic crystal, mineral crystal and sapphire crystal. Sapphire crystal is the very expensive and endurable material, it’s about 3 times stronger than Mineral and 20 times stronger than Acrylic crystal.


Ordinal number referring to a day of the month, for example: the 10th February.



Watch indicating the date, the month and sometimes the year and the phases of the moon.


Depth Alarm

Most of diver’s watches have a special feature called “depth alarm”. This function sounds a signal when wearer exceeds a preset depth.


This clasp mechanism found on most high-end watches derives its name from the French adjective Deployant - which means to unfold, unfurl or spread out. Commonly and mistakenly called Deployment, the Deployant clasp is an expanding metal clasp that permits both metal and fabric bracelets to close invisibly around the wrist.



Indicating "face" or plate of metal or other material, bearing various markings to show, in ordinary watches and clocks, the hours, minutes and seconds. Dials vary in shape, decoration, material, etc. The indications are given by means of numerals, divisions or symbols of various types.

An aperture dial has openings (apertures) through which the time indications can be read.
A thirteen-piece dial comprises 12 enamelled cartouches for the hours set around a thirteenth central enamelled piece, often decorated and with the maker’s signature.
A calendar dial gives calendar indications such as the day, date, month, year and religious festivals.
A multiple time zone dial (see complication) gives the time in two or more zones.
A dial with tide gauge (see complication) gives high and low tide times for a given location.
A regatta dial (see complication) has a countdown function enabling competitors to position themselves as near as possible to the starting line in the minutes leading up to the race.
An orienteering dial (see complication) features a hand which, driven by a specific wheel and making one complete revolution of the dial in 24 hours, shows North when the hour hand is pointed towards the Sun.
A diving dial (see complication) indicates surfacing time and possibly also decompression stops and times.


Digital watch

Digital watch is a watch that shows the time with electronic digits and using batteries for power.



(in French: trotteuse)
Refers to a seconds-hand, especially a centre seconds-hand, that moves forwards in little jerks.



Indication of time or other data, either by means of hands moving over a dial (analogue display) or by means of numerals appearing in one or more windows (digital or numerical display); these numerals may be completed by alphabetical indications (alphanumerical display) or by signs of any other kind. For example: 12.05 MO 12.3 = 12 hours, 5 minutes, Monday 12th March. Such displays can be obtained by mechanical electronic means.

Watch Display

Dual Time watch

A watch which shows current local time and additionally one other time zone.

Watch term - Dual-time-watches


French term (but commonly used in English-speaking countries) for a movement blank, i.e. an incomplete watch movement which is sold as a set of loose parts, comprising the main plate, the bridges, the train, the winding and setting mechanism and the regulator. The timing system, the escapement and the mainspring, however, are not parts of the "ébauche".



A vitreous substance whose main component is silica mixed with oxides (transition metals) that create a vast palette of colours. Enamel is used to decorate metal surfaces, in particular gold, silver and copper. Translucent enamel allows the passage of more or less light, for example the opalescent enamels that give a sought-after milky quality to certain pieces.
Champlevé enamel, Cloisonné enamel, Painting on enamel


End of energy

The end of energy in a "mechanical" watch is indicated by the seconds-hand, which jumps every two, three or four seconds.

End of life

The end of battery life in a "quartz" watch is indicated by the seconds-hand, which jumps every two, three or four seconds.


To set in motion, to connect two mechanical systems by means of a mechanical, electrical or other device. When a watch is set to the right time, the winding stem engages with the sliding pinion and the intermediate wheel to move the hands.


Set of parts (escape wheel, lever, roller) which converts the rotary motion of the train into to-and-fro motion (the balance). This mechanism is fitted between the gears and the regulating organ. Its function is to suspend the gears’ motion at regular intervals and to supply energy to the balance.
The main types of watch escapement are:
recoil escapements (verge or crown wheel)
dead-beat escapements (cylinder, virgule, double virgule)
detached escapements (lever, detent)
The lever escapement is by far the most common today. Exceptional watches may be fitted with a different kind, often a detent or virgule escapement. In terms of escapements, one can historically speak of the lever and indeed the Swiss lever type, given that the Swiss lever escapement is the most widely used today because it is especially suited to watches and chronometers.



French term for the method of manufacturing watches and/or movements by assembling their various components. It generally includes the following operations: receipt, inspection and stocking of the "ébauche", the regulating elements and the other parts of the movement and of the make-up; assembling; springing and timing; fitting the dial and hands; casing; final inspection before packing and dispatching.


French term for a watch factory which is engaged only in assembling watches, without itself producing the components, which it buys from specialist suppliers.

Factory, works

In the Swiss watch industry, the term manufacture is used of a factory in which watches are manufactured almost completely, as distinct from an "atelier de terminage", which is concerned only with assembling, timing, fitting the hands and casing.

Fly-back Hand

In a chronograph with analogue display, an additional centre seconds-hand which can remain superposed on the other one as it moves, can be stopped independently and then made to "fly back" so as to catch up with the other hand, can be stopped and reset to zero together with the other hand. In chronographs with numerical display, a "function" having the same effect.


Full calendar watch

Shows the date, the day of the week, the month and moon phases (new and full moons separated by the first and last quarters).

full calendar watch


Most water-resistant watches are equipped with gaskets to seal the case back, crystal and crown from water. Gaskets need to be checked every couple of years to maintain water resistance.



The case but also the movement’s plate and bridges can be gilded.

Glass, Crystal

Thin plate of glass or transparent synthetic material, for protecting the dials of watches, clocks, etc.



Decoration found on the dials of high-end watches.



A feature that stops the second hand when the stem is pulled out as far as it will go. This allows you to set the exact time.


Indicator, usually made of a thin, light piece of metal, very variable in form, which moves over a graduated dial or scale. Watches usually have three hands showing the hours, minutes and seconds.



Science of time measurement, including the art of designing and constructing timepieces.


Movement transmitted by a mechanical part. In a lever escapement, the impulse occurs via the impulse surface of the wheel tooth and the pallet.


A watch’s indicators are its dial and hands.



A steel-nickel alloy whose low coefficient of expansion was discovered by Charles Edouard Guillaume. Invar (abbreviation of invariable) belongs to the Elinvar family of metals which encompasses ferronickel alloys whose thermoplastic coefficient is a negligible -10°C to +30°C. These alloys are used to make compensation balances for watches.



Equal periods of time. A watch's ability to maintain its rate as the mainspring unwinds.


Bearing, endstone or pallet used for reducing friction. Generally made of synthetic material, except for the precious or semi-precious stones (ruby, sapphire, garnet) which are sometimes used in "de luxe" watches.


The international term for the jewels (rubies) in a watch movement that are used as bearings for pivots to reduce friction. The movement of a quality watch has between 15 and 21 jewels.


Jumping hour

A means of display in which the hour, shown through an aperture, instantly changes every 60 minutes



The unit of measurement of the purity of a gold alloy.
A 1k alloy contains 1/24th of its weight in pure gold.
An 18k alloy is 18/24th pure gold.
Pure gold is 24k. The unit of weight for precious stones. One karat equals 0.20 grams.


A device similar to the tourbillon, the difference being that the cage is driven by the third wheel. Invented by Bonnicksen, a Danish watchmaker established in London


The tooth on a pinion.



Part of a watch or clock escapement, made in steel or brass. The lever, whose form suggests a ship’s anchor, has a dual function: it transmits energy from the spring via the wheels to the balance in order to maintain its oscillations. It also controls the movement of the wound gears.



Traditional unit of measurement used to measure the diameter of watch movements.


A thin metal rod fixed between the case horns for attaching the watch strap.
1.Lug 2.Case horns 3.Case 4.Watch strap


Luminous paint

Self-illuminating paint that is put on the hands and markers to read the time in low light situations.


Main Plate

Base plate on which all the other parts of a watch movement are mounted (part of the "ébauche").



The driving spring of a watch or clock, contained in the barrel.


Manufacture d'horlogerie

French term for a watch factory which itself produces the components (particularly the "ébauches") needed for the manufacture of its products (watches, alarm and desk clocks, etc).


Marine Chronometer

Highly accurate mechanical or electronic timekeeper enclosed in a box (hence the term box chronometer), used for determining the longitude on board ship. Marine chronometers with mechanical movements are mounted on gimbals so that they remain in the horizontal position is necessary for their precision.


Minute Repeater Watch

Minute-repeater watches are watches with a mechanism of telling the time by making a sequence of sounds. Minute-repeater watches are created to strike the hours, quarter-hours and minutes. Every strike is characterized by its own distinctive sound and frequency. This effect is achieved with the movement incorporating two different hammers with strike gongs that produce contrasting vibrations and tones.

Middle (of watch-case)

Middle part of the case, in which the movement is fitted.


Assembly consisting of the principal elements and mechanisms of a watch or clock: the winding and setting mechanism, the mainspring, the train, the escapement, the regulating elements. "Anatomically", the movement consists of the "ébauche", the regulating elements and the other components.

Nickel silver (German silver)

A silver-white alloy of copper, nickel and zinc developed in France circa 1820 by Maillot and Chorier from whom it takes its name.


An enamel-like alloy of lead, copper, silver, sulphur and sal ammoniac (ammonium chloride). Niello paste is applied over incised gold or silver then fired in the enamellist’s furnace. Excess niello is filed off and the surface smoothed. Polished niello cases were fashionable shortly before wristwatches were introduced.

Observatory chronometer

A chronometer which has received an official rating certificate from an observatory.

Official rating certificate

A document, issued by an Observatory or an official ratings bureau, that certifies the quality of a watch which has proven, in trials, to meet with a given standard. Only a watch that has received an official rating certificate can be called a chronometer.

Oil sink

A cavity in bearings for a drop of oil.


Oscillating weight (Rotor)

In a self-winding movement, a heavy metal disc that turns freely in both directions to wind the mainspring.



When a pendulum or balance oscillates it moves between two extreme positions (A’ and A’’). The movement from one of these positions to the other and back equals one oscillation. Usually a balance produces 9,000 oscillations an hour, equivalent to 18,000 vibrations.
1 oscillation = 2 vibrations



A device such as a pendulum or balance that produces the oscillations that divide time into equal units: a balance spring in a mechanical watch; a quartz in a quartz watch.


A tiny motif cut out of gold or silver and used to decorate enamelwork.



The action of coupling a spring with its balance.


In a lever escapement, a small parallelepiped of ruby, sapphire or garnet, set in each of the lever’s arms; one is the entrance pallet and one is the exit pallet.



The various elements used to make or repair a watch. In the latter case, these are spare parts.


A group of gems set closely together to cover an entire surface.


Pawl (Click)

A lever with a "beak" which, activated by a spring, engages with the teeth of a wheel, usually to allow the wheel to turn in one direction only.


Pellaton (winding system)

The Pellaton automatic winding system was developed by Albert Pellaton, then technical director at IWC, and patented in 1946. The system was further improved in 1950.


The part of a pocket watch that is fixed to the case middle. The different parts of the pendant are the pipe, the head and the neck. The foot is the invisible part that is soldered inside the case.

After the mid-nineteenth century, the pendant, crown and bow formed a whole whose shape and size were designed to complement the case.

In a wristwatch, the pendant is reduced to a small cylindrical stem on which the winding crown turns. Pendant or keyless winding is by means of the crown as opposed to the winding system on early pocket watches by means of a key or pushbutton.


Perpetual calendar

Devised to incorporate the specificities of the Gregorian calendar. It is perpetual because it automatically adjusts to months with 30 days and to the 28 or 29 days in February. For this, it incorporates a mechanical memory whose sequences are repeated every 48 months to correspond to the cycle of leap years.



A heavy body suspended from a fixed point from which it can swing freely to and fro. A clock pendulum comprises the suspension, which can be a spring, knife-edge or a wire, the generally cylindrical metal or wood rod, and the bob, which is the weight at the end of the rod.

Galileo used a pendulum in his astronomical observations (1595). Huygens expanded on Galileo’s theory to build his pendulum clock in 1657. It was a further twenty years or so before his invention reached the Jura, where the Mayet brothers, both blacksmiths, applied it to what appears to be the ancestor of the Comtois clock.


A watch part, generally with 6 to 14 leaves (teeth). The different parts of the pinion are the leaves, the seat to which the wheel is riveted, the shank and the pivots.



A part that runs in a fixed support (bearing).



A point is a hundredth of a carat or 0.01 ct.



To give a smooth and shiny finish. Example: mirror polish (or black polish).

Power reserve, Indicator

The time the watch will continue to function before the mainspring must be wound.

power reserve indicator

Precision timer

The person who times chronometers and watches of similar quality.


A button that commands a function, for example to open a case cover or to start and stop a chronograph.

push button


A chronograph or sports counter whose dial includes a pulsometric scale to measure the number of heartbeats per minute. Usually calibrated for 15 or 30 beats, the hand is stopped at the patient’s 15th or 30th heartbeat; the dial indicates the frequency per minute.



Physical Vapor Deposition. Method of coating thin watch cases by integrating titanium particles and then depositing gold for color (usually comes in black finish).


Silicon dioxide. Also called rock crystal. Quartz has the specific property of vibrating at a very high frequency (32 MHz) placed under electric current. Under certain conditions, it imparts its own vibration frequency to the circuit. This property has been used in electronic watches since the 1970s.


Quartz oscillator

The regulating organ in a quartz clock or watch.


A minute scale on a dial that resembles a railway track.



A saw-toothed wheel. The ratchet wheel in a watch is a toothed wheel that is fixed by a square hole to the barrel arbor. A click (pawl) prevents the ratchet wheel from turning in the unwinding direction. In a striking mechanism, the hour-ratchet or hour-rack is a toothed sector that lifts the hammer to strike the hours.



The functioning of a timepiece evaluated in terms of its regularity. Daily rate is the amount of time a watch gains or loses over 24 hours compared with a reference time.


Addition of a second hand to measure split times.

Regulating elements

Set of parts comprising the regulating system (sprung balance) and the escapement (escape wheel, lever and roller).


A clock with non-coaxial hour and minute hands. The size of the hands and their position reflect their importance: the minute hand is always the larger and is positioned in the centre of the dial. Observatories and Manufactures once referred to highly precise regulators, also known as parent clocks, to set their watches to time.



The final and complete inspection of the watch with its mechanism and aesthetics, just before it leaves the manufacturer. Both rate and appearance are inspected.


Watch that strikes the hours by means of a mechanism operated by a push-piece or bolt. There are various types of repeaters. Quarter-repeater: sounding a low note for the hours and a "ding-dong" for each of the quarters; Five-minute repeater: striking the hours, quarters and five-minute periods after the quarter; Minute-repeater: striking the hours, quarters and minutes; Grande sonnerie (grand strike): striking the hours and quarters automatically and repeating when a push-piece is pressed down; Chiming repeater: in which the quarters are struck on three or four gongs of different pitch.


An hour, minute, seconds or calendar hand which moves across a scale and, at the end of its cycle, returns immediately to zero to begin again.



A circular mass held by spokes to form the balance.

Roman numerals

I, II, III, etc.
Roman numerals have traditionally been used on clock and watch dials. IV is often given as IIII to create visual symmetry with the VIII. Only the IX is written using the subtractive principle.



Half-disc of heavy metal, which is made to rotate inside the case of an automatic watch by the energy produced by the movements of the wearer's arm. Its weight tends always to bring it back to the vertical position. Demultiplied by a specially designed device, its rotations continually wind the mainspring of the watch.



A very hard red stone that is a type of corundum (crystallised aluminium oxide). Ruby is especially suited to making bearings (jewels) for the watch’s different moving parts and the organs of the escapement, thereby reducing friction to a minimum. Drilled rubies were used for the first time by Nicholas Facio de Duillier in 1704.

Watches today use synthetic rubies known as jewels. Drilled and polished, they are used as bearings for the different pivots to minimize friction and wear. As a general rule, a simple mechanical watch, i.e. one that indicates hours, minutes and seconds, should have at least fifteen jewels at the points most exposed to friction.

Safety roller

In a lever escapement, a disc which limits the fork’s movement.


Basic unit of time (abbr. s or sec), corresponding to one 86,000th part of the mean solar day, i.e. the duration of rotation, about its own axis, of an ideal Earth describing a circle round the Sun in one year, at a constant speed and in the plane of the Equator. After the Second World War, atomic clocks became so accurate that they could demonstrate the infinitesimal irregularities (a few hundreths of a second per year) of the Earth's rotation about its own axis. It was then decided to redefine the reference standard; this was done by the 13th General Conference on Weights and Measures in 1967, in the following terms: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental state of the atom of caesium 133". Conventionally, the second is subdivised into tenths, hundredths, thousendths (milliseconds), millionths (microseconds), thousand-millionths (nanoseconds) and billionths (picoseconds).

Secret spring

A spring that releases the cover on a hunter watch case.

Setting (to time)

Process of bringing the hands of a watch or clock to the position corresponding to the exact time.

Shock Absorber

Resilient bearing which, in a watch, is intended to take up the shocks received by the balance staff and thus protects its delicate pivots from damage.

Simple calendar (watch)

Watches that show the date, i.e. the number, in order, of each day in the month. Certain simple calendars also display the names of the months. A simple calendar does not automatically take months with less than 31 days into account, or leap years, and must therefore be adjusted five times a year.


Skeleton watch: watch in which the case and various parts of the movement are of transparent material, enabling the main parts of the watch to be seen.

Step motor

An electric motor in which at least one part moves as a series of steps. Also known as a Lavet motor after its inventor Marius Lavet, the step motor equips the majority of quartz watches.


In watchmaking, a precious stone used as a bearing, endstone or pallet-stone, known internationally as jewels. The majority of stones (jewels) used in watches today are synthetic. Their role is to minimise friction.

A precious stone is a hard and rare crystalline mineral, used in jewellery and for certain parts of precision instruments such as watches, clocks, and compasses. The four precious stones are the diamond, ruby, sapphire (both corundums) and emerald (beryl).
A fine stone is a mineral having the same properties as a precious stone though to a lesser degree. The main fine stones are topaz, spinel, tourmaline, garnet and quartz (rock crystal, agate, amethyst).



Timekeeping instrument which can be used for measuring intervals of time. When this is done, the time display is partly or wholly lost until the hands are reset.

Striking-work, Striking-Mechanism

In a watch or clock, automatic or hand-operated mechanism that strikes the hours, etc, or rings an alarm-bell (v. repeater).

Super accurate

A watch that is accurate to +/- 10 seconds per year. A technology that uses quartz crystal oscillators working with an integrated circuit, assuring up to 10 times more accuracy than a conventional quartz watch.


Instrument for measuring speed. In watchmaking, a timer or chronograph with a graduated dial on which speed can be read off in kilometres per hour or some other unit (see timer).


Stopwatch or chronograph function with a scale that measures the distance of something from the wearer of the watch through the amount of time it takes sound to travel.


Heat treatment after quenching whereby metal is heated then slowly cooled. Tempering increases mechanical resistance by reducing the brittleness induced by quenching.


French term denoting the process of assembling watch parts for the account of a producer.


French term for an independent watchmaker (or workshop) engaged in assembling watches, either wholly or in part, for the account of an "établisseur" or a "manufacture", who supply the necessary loose parts.

Time zone

In order to standardise time measurement in each country, since 1883 the Earth has been divided into twenty-four time zones, the first of which is intersected by the Greenwich meridian, which is the prime or zero meridian. Each point within a given time zone has the same legal time.

time zone


Instrument used for registering intervals of time (durations, brief times), without any indication of the time of day.


A projection on the edge of a gear, escapement wheel, ratchet wheel, etc.



Device invented 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 centre. The escape pinion turns about the fixed fourth wheel. The case makes one revolution per minute, thus annulling errors of rate in the vertical positions.


Triple date calendar

Complication that provides month, day and date.


A two-pronged metal instrument mounted with quartz crystals. An electromagnet maintains the crystals’ vibrations. These vibrations activate a pawl which advances the drive wheel, one tooth at a time.

Under-dial work

Collective term for the mechanisms, such as for striking, a calendar or motion work, between the dial and the dial plate.

Under dial work

Universal (watch with universal hours)

A watch whose dial shows the time of places in different time zones.


Universal Time (UT)

Since 1972, a continuation of Greenwich Mean Time (GMT) which is mean solar time at the Greenwich meridian. Universal Time (UT) is a measurement of time based on the Earth’s rotation. It is therefore influenced by its irregularities due, among other factors, to the tides produced by the Sun and Moon. There are several Universal Times, one of the most important being Coordinated Universal Time (UTC). This international standard is the basis of civil time. It is derived from International Atomic Time (TAI), itself based on the atomic definition of the second and measured using a series of atomic clocks.

Vagues de Genève

Synonym of Côtes de Genève. A decoration of undulating lines, like waves, frequently used to embellish superior quality movements.

vagues de geneve


Uses air friction to slow a moving part, for example the arm on a gravity escapement.


Silver covered with a thin layer of gold.


Movement of a pendulum or oscillating body between two extreme positions (A’ and A’’). The balance of a mechanical watch generally makes five vibrations per second, equivalent to 18,000 vibrations/hour (2.5 Hz). A more accurate mechanical watch makes 10 vibrations per second or 36,000 vibrations/hour (5Hz). A quartz watch makes 64,000 vibrations per second ( 32 MHz). An oscillation ("tick-tock") equals two vibrations (although oscillation is sometimes incorrectly used to refer to a vibration).

Watch Material

Loose parts, components either for producing watches or for repairing them. In the latter case, they are often called "spare parts" or "repair material".

Water Resistant

Made to prevent water from entering. Water-resistant case, watch-case whose joints are made to prevent moisture from entering.


No watch is 100% waterproof.


A circular component that rotates around an axis and whose function is to transmit power or motion.


White on

Analog watch that is able to display functions at the touch of a button. An easily legible white numeric display appears on the inside surface of the crystal when any digital function is activated.


The action of tightening the mainspring coiled inside the barrel by means of the winding crown (in a hand-wound watch) or the rotor (in a self-winding watch).


Operation consisting in tightening the mainspring of a watch. This can be done by hand (by means of the crown) or automatically (by means of a rotor, which is caused to swing by the movements of the wearer's arm).

Winding mechanism

The mechanism which tightens the mainspring in a watch or lifts the weights in a clock. It comprises about ten parts (see drawing).
The winding and hand-setting mechanisms have nowadays some parts in common.


A metal applied by electrodeposition (electroplating) to protect iron and steel.

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