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altimeter rotating bezel that measures the altitude.

atmosphere measurement of pressure. One atmosphere is equal to the pressure of one kilgram per square centimer. In watchmaking, an atmospheric measure is the amount of air pressure at sea level that a watch can withstand; 1 ATM = 33.9 feet of water, and 3 ATM = 100 feet.

automatic watch see self-winding watch.


balance mechanical watches are regulated with the balance and the balance-spring.

balance-spring also called the "hair spring." In a mechanical watch, attached to the balance and cock, and made of metal alloys. Its length determines the amount that the balance regularly oscillates; the shorter the spring the faster the watch runs.

barrel spring this spring’s tension controls the amount of energy transmitted to the movement. Hooked to the barrel and the arbor, when it is tensed it releases energy.

beat the number of times per second (beats per second (BPS) or per hour (BPH) that a balance wheel goes through a full arc of motion.

bevel furrow or groove cut at an angle that is either over or under, but not equal to, 90 degrees.

bezel groove or flange with a slanting surface designed to hold the beveled edge of an object; on watches, it is the ring that holds the crystal on the top of the watch.

blued screws steel screws which are hardened by being heated to high temperatures to relieve stress in the metal. The high temperature gives the steel a permanent blue.

bottom plate supporting the bridges, which are often on the top of the plate, the movement, the dial, and the holes where the jewels are inserted.

bridge balance cock attached to the bottom plate with pins.

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cabochon a semi-spherical precious stone, often placed at the end of a crown, that is uncut but highly polished.

calendar display indicating the day, month, date, year, and/or moon phase.

caliber / calibre manufacturer's identification of a movement used in a watch. The caliber used to refer to the diameter of the movement measured in "Parisian lines," where 1 = 2.256mm.

carat gold content of a metal alloy measured on a 24-part scale. 24kt = almost 100% gold, 18kt = 75% and 14kt = 58.5%.

case container protecting the dial and movement, and made up of the caseband, caseback and the bezel.

center seconds see sweep seconds.

chamfering see bevel.

chronograph "time writer," watch that measures a particular event, such as a race, with intervals of seconds to hours, and which can be reset to zero.

chronometer extra-precise timepiece that has been tested extensively by COSC or another regulatory body.

complete calendar calendar display that indicates the day, date and month.

complication any of the available multi-functions added to a watch, such as a minute-repeater, tourbillon, calendar, and stopwatch.

COSC Swiss Controle Officiel des Cronometres, the independent regulatory organization that rigorously tests and certifies (or fails) watch movements.

crown button used to wind and/or set a watch.

crystal the glass or other clear covering for the dial. Usually made of mineral glass or sapphire.

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date display indication of the date either with a dial, hand, or a digital display.

day / date watch that indicates the day of the week and the date.

deployant / deployment hinged metal clasp on a watch strap or bracelet which is opened so that you can put on the watch.

dial the face of a watch which shows the time; normally has at least two hands for the hours and minutes.

dual time watch that tracks the local time and the time in another place, indicated with an inset dial or an extra hand.


ebauche the movement without its escapement, balance, the main spring, the balance-spring, the dial, or the hands.

elinvar see Invar.

energy in quartz-crystal watches, a battery provides the necessary energy to run a watch. In mechanical models, there is a spring that does this.

escapement a mechanism made up of the escapement wheel, lever, and discharging roller, which act to control the wheel movement and to provide pulses to the pallets and thus to the balance.

exhibition back see skeleton movement.

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facette miniature surface which is usually flat.

fast beat watch a watch that has a balance wheel which rotates 22,000 or more beats an hour.

fine regulating see index.

frequency in watches, the number of oscillations per second of a pendulum or other vibrating object.

fusee grooved pulley that equalizes the main spring by controlling its winding or unwinding.

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galvanished finish the base metal of the movement is coated with a layer of gold or rhodium.

glucydur copper and glucinum stainless, non-magnetic alloy used in watchmaking for internal parts.

GMT Greenwich Mean Time, marking the middle of a solar day, is the time as measured from zero degrees latitude, in Greenwich, England.

going train made up of the going barrel, which drive the center wheel. The center wheel drives the third wheel, then the third wheel drives the second wheel. The second wheel drives the escapement wheel.

guilloche complex engraving that appears as lines or circles which interlock.


hard back case made of metal (opposite from a skeleton or exhibition back).

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Incabloc standard brand of watch shock absorbers.

index instead of a number, a marking that indicates the hour.

inner cover usually used only in pocket watches, the inner cover is an extra one under the main back cover.

Invar special alloy related to beryllium and used for watch parts because it is not magnetic and resists rust.


jewels small gems or synthetic stones used as bearings and pallet-stones for the lever and impulse pin that reduce friction, and thus wear and abrasion in the movement. Also called rubies.

jump hour a spring that causes a hand or other part of a watch to suddenly advance. A jump hour watch displays the hour through a dial window.

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lap time see split hand.

lever escapement eighteenth century invention which is made up of an escape wheel, a lever, and a balance wheel; the only one used now in making mechanical watches.

lug the parts of a watch that go between the case and around the bracelet or strap.

lunette a bezel or circular ornamentation made of glass.

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manual-winding watch the springs on this sort of watch are wound with a winding-crown, usually done daily.

mechanical watch uses a balance or pendulum to run.

micro-rotor automatic watches have this contained in their movement, thus decreasing the required thickness.

mineral glass used for the exterior dial to make a watch more scratch-resistant than with the use of synthetic glass.

minute-circle the markings on a watch dial that indicate minutes.

minute-repeater indicates the time in hours, quarters, and minutes by means of a push-piece or slide.

moon phase on a watch, a complication that involves a dial showing the changes in the moon’s phases as it goes through the 29 ½ day cycle around the earth.

motion work train under the watch dial which sends the minute-pinion rotation to the hour wheel, this showing the exact time.

movement the main grouping of watch machinery that produces or transmits motion.

movement blank see ebauche.

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pallet a piece of the lever escapement, this is usually in the shape of a ship’s anchor.

perpetual calendar extremely elaborate complication that keeps track of the day, month, date, and sometimes even the moon phase, zodiac signs, decade, or century, and which adjusts for the length of the month and for leap years.

plate metal piece that holds up the bridges and other parts of the movement.

power-reserve the length of time beyond 24 hours that a watch will run without needing winding; ordinarily about 10 to 16 hours.

pre-owned watch watch that has been owned by another person.

pulsimeter a chronograph with an extra dial or timer that gives the rate of a pulse per minute.

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quartz movement movement that is powered by a battery, and keeps time based upon the vibrations of a quartz crystal.


rattrapante see split-seconds chronograph.

regulateur watch with a dial that emphasizes the minutes, usually shown in a ring around the dial, with seconds and hours in small inset dials.

regulator device inside a watch that speeds it up or slows it down to allow the more precise setting of the watch.

repeater strikes the hour, half-hour, minutes, seconds, or some combination of these.

retrograde mechanism that lets a hand quickly return to its original position, usually used to return to one after sixty seconds have gone by.

rubies see jewels.

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sapphire glass used for the exterior of the dial to make a watch the most scratch-resistant; the only harder substance is diamond.

self-winding watch the springs of this sort of watch are wound up by the normal movement of the wearer’s wrist through the motion of a rotor linked to the movement.

shock absorbers spring-loaded settings used for the jewels which support the balance staff, thus protecting the movement from damage due to falls or other shocks.

skeleton movement movement on a watch where the plates have been removed or trimmed so that you can see the gears and other parts.

small seconds hand often located around 6 o’clock, this is a small dial which displays the seconds, and is adjusted with a winding-crown 90 degrees from the dial.

split hand also known as lap time, a second hand that can be stopped independently of the chronograph and returned to the current time.

split-seconds chronograph also known as a rattrapante, this is a watch that has two second hands superimposed which split up in order to time more than one action.

stop second crown which can be pulled out to set the seconds on a watch more accurately.

sweep / center seconds hand a hand that displays the seconds placed in the middle of the dial, though this is often duplicated by an inset dial at the 6 o’clock position that also shows the seconds.

Swiss-made watches assembled, started, adjusted, and controlled by a manufacturer in Switzerland.

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tachometer / tachymeter counts the number of rotations to tell you how fast you travel over a measured distance.

tank rectangular watch case modeled on Cartier's WWI tank-inspired watch design.

telemeter stopwatch or chronograph complication with a scale that measures the distance of something from the wearer of the watch through the amount of time it takes for a sound to travel.

tonneau something in the shape of a barrel.

tourbillon "whirlwind," a complex mechanism requiring the highest watchmaking skills; consists of a mobile carriage carrying all the parts of the escapement. It is a regulating device which corrects for the gravity-caused differences in run time in a mechanical watch.

tritium luminous material that makes hour markers and/or hands easier to read in the dark; ideal for diving watches.

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up and down work power reserve indicator dial on a watch.



water-resistant no dust or water can penetrate, and the depth of the watch’s resistance is on the back of the case; typically measured in meters.

winding-crown button used to wind the springs of a manual-winding watch, or to change the date or position of the hands.

winding-stem the winding crown is attached to the end of this stem.

world time the time in several capitals across the world, usually shown in watches through inset dials.




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