automatic – (self-winding) watch whose movement is mechanical. An oscillating weight (the rotor) turns by the motion of your arm and winds the mainspring. The energy is transferred into mechanical energy that creates the watch movement. These watches can be shaken or manually wound if the power reserve runs out.
manual – (manually wound) a mechanical watch movement that is wound by hand.
quartz – a natural or synthetic silicon dioxide crystal used in quartz analog or solid state digital watches when activated by a battery or solar power, the thin silver of the crystal very predictably vibrates at an extremely high frequency (32,768 times per second) step motor, electric circuit block.
digital – watch that uses an LCD or LED to display a continuous reading.
analog/digital – has both a digital display and hands of a conventional analog watch.



ceramic– material used as a shield for spacecraft reentering the earth’s atmosphere, high tech ceramic is polished with diamond dust to create a highly polished finish.
gold – typically watch cases ar 18K gold because 24K is too soft.
platinum – one of the rarest precious metals as well as one of the strongest and heaviest.
stainless steel – extremely durable metal alloy consisting of steel, nickel, and composed mainly of chromium. It is virtually rustproof. It is also antimagnetic. 316L is the standard steel used in watchmaking, however Rolex uses a slightly harder and more corrosion resistant steel called 904L. 904L is generally used in chemical applications and it costs significantly more than 316L steel.
tantulum – a grey, heavy, and very hard metal. Tantalum is used to make a variety of alloys at high melting point and high strength. Tantalum is completely immune to body liquids and is a non-irrititating material.
titanium – a metal, gray in color, that is used for watch cases and bracelets. Much stronger and lighter than stainless steel and hypo-allergenic. It is 30% stronger and 50% lighter than steel. It is very resistant to salt water corrosion, making it useful for diver’s watches. Although, since it can be scratched easily, some manufacturers use a coating to resist scratching.
palladium – a rare and lustrous metal that is slightly whiter than platinum and slightly harder. It is part of the platinum group of metals. Palladium is tarnish resistant, electrically stable and resistant to chemical erosion as well as intense heat.
nickel silver – (German silver) German watch manufacture A. Lange & Sohne uses untreated German silver in their movements. German silver has a brighter and more luxurious finish, as compared to brass (which is commonly used for base plates).
brass – the most common material used for watch bridges and mainplates. It is often rhodium-plated, or even gold-plated.
bronze – an alloy used for watch cases that acquires a significant patina.
carbon fiber – a material that is made of heat compressed layers of carbon fiber.
resin – a lightweight, shock resistant material similar to plastic.
glucydur – copper and glucinum stainless, non-magnetic alloy used in watch making for internal parts. Anti-magnetic alloy that expands very little when exposed to heat. (Used for balances)



complication – any “function” added to a watch, such as a minute repeater, countdown timer, stop watch, altimeter, asthometer, pulsometer, calendar, moon phase indicator, split second chronograph, power reserve indicator, alarm, etc.
simple calendar – is a complication that shows the date of the month. A day/date shows the date of the month and the day of the week. A complete calendar shows the day, date, and the month or moon phase.
annual calendar – displays the date, day of the week and month with only one manual adjustment required per year for February (except during a leap year).
perpetual calendar – elaborate complication that keeps track of the day, month, date, and sometimes even the moon phase, zodiac signs, decade, century, and which adjusts for the length of the month and for leap years. (Accurate until 2100)
moon phase – displays: new moon, first quarter moon, full moon, and last quarter moon by means of a disk that rotates beneath a small aperture. The 29 and 1/2 day cycle of the moon.
deadbeat seconds – A hand that jumps when the second has elapsed. Generally, the jump of a hand is a distinctive feature of a quartz watch. In mechanical watchmaking, this is a function.
dual-time zone – measures local time as well as time in another time zone. Often also called, Greenwich Mean Time (GMT), a watch that has the capability of displaying two different time zones.
foudroyante – small dial that is marked 0-8. The hand on the dial completes a sweep every second which is an elapsed time of 1/8th of second for each number.
depth-alarm – a complication on a diver’s watch that sounds an alarm when the wearer exceeds pre-set depth. The alarm stops when the diver ascends above pre-set depth.
flyback – function that allows a chronograph to be reset to zero without having to stop the chronograph first.
jump hour – a display in which the hour, shown through an aperture, instantly changes every 60 minutes.
split-seconds chronograph – or “rattrapante” or “doppelchrono” has two seconds hands, the first push starts both hands together, the second push stops one hand while the other continues, and another push allows the stopped hand to catch up with the moving seconds.
worldtimer – a timepiece that displays the current time in any part of the world, from 24 up to 37 timezones.
yacht countdown timer – a countdown timer that sounds warning signals during the countdown to a boat race.
minute repater – a highly complicated function that can strike the time in hours, quarters, or minutes by means of a push piece. Before the light bulb, minute repeaters allowed their owner to listen to the time without the need for light. Strikes/Chimes the hour, half hour, minutes, seconds, or some combination of the two.
tourbillon – (also called “whirlwind”) eliminates errors of rate due to earth’s gravity of vertical positions. A complex mechanism requiring the highest watch making 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.
power reserve indicator – a sub dial used to show how much power remains before the watch stops.
tidegraph – tides are the periodic rise and fall of the water of oceans, seas, bays and other bodies of water caused mainly by the gravitational interactions between the Earth, Moon and Sun. Tides rise and fall about every six hours. The tide graph indicates tidal movement based on the Moon’s transit over the meridian and the lunitidal interval.
equation of time – The equation of time is the difference between true solar time and mean time. True solar time, given by sundials, varies from day to day because of the Earth’s elliptical orbit, and according to the longitude of the point of observation. Mean time, given by watches, ignores these variations and for every day of the year mathematically divides time into equal hours. Apparent solar time, can be ahead (fast) by as much as 16 minutes 33 seconds (around 3 November), or behind (slow) by as much as 14 minutes 6 seconds (around 12 February).
chronograph – stopwatch function that uses sub dials to keep track of second, minutes, and hours.
retrograde – 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 (not to be confused with “regulator dial”).
slide rule bezel – a rotating bezel that is printed with a logarithmic scale and assorted other scales and is used in conjunction with fixed rules of mathematics to perform general mathematical calculations or navigational computations.
tachymeter – instrument for measuring speed over a measured distance. A racing car covers 1 mile in 30 seconds. The sweep second hand, when stopped at the end of the mile, would point to the 120 on the tachometer. The average speed in 120mph.
alarm – a function that can be used to set an audible (typically buzz sound) alarm.
dive bezel – a graduatated bezel that measures 0-60 and rotates in only one direction.
telemeter – 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 for sound to travel.



oscillating frequency – (also referred to as vibrations per hour – VPH, or beats per hour BPH) 18,000 VPH or 2.5Hz, 21,600 VPH or 3Hz, 28,800 VPH or 4Hz, 36,000 VPH or 5Hz, 43,200 VPH or 6Hz, 72,000 VPH or 10Hz. movement of a pendulum limited by 2 extreme positions. The balance of a mechanical watch generally makes 5 or 6 vibrations per second (18,000-21,600 per hour.) A high frequency watch makes 8-10 vibrations per second (25,200/28,800/36000/43,200 per hour) Vibrations per hour is also called BPH (“beats per hour”).
stop second – (same as “hacking”) crown which can be pulled out to set the seconds on a watch accurately. a feature that stops the second hand when the stem is pulled out as far as it will go and allows you to set the exact time.
observatory chronometer – similar to a standard chronometer, but even more accurate. The movements are adjusted in 5 positions and generally must perform within a deviation of 0.6 seconds per day. Historically these were used at scientific observatories, and for expeditions where accuracy is paramount.
uni-directional bezel – a bezel that rotates only one way (a dive bezel, for example, only moves one way, because it is used to count how much air is left in your tanks, and you would not want your bezel to accidentally go back, because it could be extremely dangerous if you stay under too long).
amplitude – is the number of degrees of rotation of the beat (oscillation) of the balance wheel, either clockewise or counterclockwise. The ideal degree of amplitude on each swing of the balance wheel is 275 to 300 degrees. (Lower than 275 degrees is generally considered slow and can adversely affect the +/- average rate of the watch.)
anti-magnetic – (A/m) unaffected by magnetism. If the parts most affected by a magnetic field (balance, balance spring and escapement) are made of non-magnetic materials or the materials are blocked from magnetism by a soft metal cage, the watch is called anti-magnetic. Typically this type of watch has a soft iron cage around the movement to prevent magnetic fields from affecting the timekeeping, however, Omega has a movement where all the critical parte are antimagnetic so no soft-iron cage is needed.
beat – the number of times per second (BPS) or per hour (BPH) that a balance wheel goes through a full arc of motion or the vibrations per hour (VpH) (half oscillation, or “tick”) of a movement.
atelier – a workshop where wristwatches are assembled.
horology – science of time measurement, including the art of designing and constructing timepieces.
chronometer – A chronometer is a high-precision watch capable of displaying the seconds and housing a movement that has been tested over several days, in different positions and at different temperatures, by an official neutral body (COSC). Each chronometer is unique, identified by a number engraved on its movement and a certification number given by the COSC. Each movement is individually tested for several consecutive days, in 5 positions and at 3 temperatures. Each movement is individually measured. Any watch with the denomination “chronometer” is provided with a certified movement. Generally accurate to 5 seconds per day, or better.
C.O.S.C. – Controle Officiel Suisse des Chronometres (Official Swiss Chronometer Testing Institute) they test watches for several consecutive days, in 5 positions and at 3 temperatures. They either pass or fail the watch movement. If the watch passes it is certified as a “chronometer”.
atomic timekeeping – quartz watch that is controlled by a radio signal from a cesium atomic clock. The result is extremely accurate time that can be measured on instruments. (radio-controlled)
solar time – solar time, given by sundials, varies from day to day because of the Earth’s elliptical orbit, and according to the longitude of the point of observation.
time zone – the world is divided into 24 time zones spaced at intervals of 15 degrees in longitude. The zones start at 0 with Greenwich. Within each time zone, the hour and minute of the day is defined to be the same. Time zones are usually specified by the number of hours they differ from GMT. EST is GMT 5 hours.
caliber – the size and configuration of a watch movement. The diameter of the movement measured in “Parisian lines,” where 1=2.256mm. Also a generic term for a watch movement.
cambered – curved or arched dial, bezel or sapphire crystal.
column wheel – upright castle shaped wheel in a chronograph that acts as a sliding link to operate the various levers that set the chronograph functions in motion, generally more accurate type of chronograph.
ebauche – (raw movement) unassembled movement, without escapement, balance, hairspring, or mainspring.
marine chronometer – a highly accurate timepiece enclosed in a box that is used for determining the longitude on board a ship. A marine chronometer is mounted on gimbals so that they remain in a horizontal position to maintain their precision.
manufacture – the french word for a watch factory that builds at least one watch movement (caliber) in-house. a factory that makes its own components and assembles at least one complete movement (caliber), in-house.
hallmark – a mark stamped into the case of the watch to provide information about the degree of purity of the metal used, the country of origin, the year of manufacture, the identity of the case’s maker, trademarks, reference numbers, and/or serial numbers.
professional watch – purpose built watches designed to be utilized in professional situations such as: diving, flying and exploring (sometimes referred to as “tool” watches).
oscillating system – hairspring and balance form the oscillating system. Two vibrations of the balance make the tick-tack sound of a mechanical watch known as oscillation. The travel of the balance wheel from one extreme to the other and back again.
regulator – the device inside a watch that speeds it up or slows it down to allow the more precise setting of the watch.
free-sprung balance –
dive watch – ISO 6425 Dive watch standard Divers’ watches must be water resistant to 330 ft minimum (100 meters). They must also feature a time controller and comply with standards provided by NIHS 92-11 (ISO 6425) : luminosity, shock resistance, anti-magnetism, band solidity.
co-axial-escapement – invented by George Daniels, is a type of modern watch escapement mechanism invented by English watchmaker George Daniels. Considered by many to be one of the most significant horological advancements since the invention of the lever escapement, the co-axial escapement functions with virtually no lubrication thereby eliminating one of the shortcomings of the traditional lever escapement.
Swiss made – legally protected indication of Swiss origin. Under terms of the Swiss Federal Council ordinance of December 23, 1971, it can apply only to watches with: -Swiss Movement -Assembled in Switzerland -Final inspection must be done in Switzerland
Swiss movement – in order for a watch to state that it has Swiss Movement it must: -be assembled in Switzerland -be tested in Switzerland -have 60% of the parts from Swiss origin
regulator dial – a watch where the hour and minute hands are not on the same, but separate, pinions. Generally a “regulator watch” (not to be confused with “retrograde”) has an hours subdial at 12 o’clock, a seconds subdial at 6 o’clock and a central seconds hand.
Geneva seal – quality seal the displays the City of Geneva coat of arms. Watches must meet eleven strict criteria to be awarded the Geneva seal.
water-resistance rating – watches tested ability to withstand water from entering the case to a certain depth. Common water-resistance measurements (1 ATM = 1 BAR = 10 METERS = 33.3 FEET).
ISO 22810 Water resistant standard – for a watch company to state “water-resistant” it must withstand overpressure of at least 2 bars or 20 meters.
helium escape valve – a helium escape valve is required for divers who spend a long time in hyperbaric chambers and breath helium enriched gas. The helium molecules are lighter than air and can therefore penetrate the watch. When a pressurized enclosure, such as a diving bell, surfaces and is depressurized the helium rushes out of the watch so quickly that the crystal on the watch pops out. To avoid this the helium escape valve releases this helium from the watch while resurfacing. This allows helium to escape without water entering the watch.
screw down crown – seals the crown against the case to prevent water penetration.
incabloc – a brand of shock absorber for mechanical watches designed to protect pinions or jewels.



guilloche – is a decorative engraving technique in which a very precise intricate repetitive pattern or design is mechanically engraved into an underlying material with fine detail
rhodium-plating – (or ruthenium or gold plating) are often on watch movements.
chamfereing – (same as “beveling”) of the edges plates, bridges or parts (typically to a 45 degree angle).
stripes – Geneva stripes, also called “Cotes de Geneve” or “Glashutte Ribbing”) A form of decoration in higher grade watch movements the consists of vertical stripes that are often applied to the bridges, main plate and other parts.
cotes circulaires – (also called “fausses cotes decoration”) It is a similar decoartion to Geneva stripes but instead of vertical lines in consists of circular, concentric lines.
perlage – is a surface decoration comprising of an even pattern of partially overlapping dots applied with a quickly rotating grinding drill tip. It consists of small, overlapping circles, and is typically applied to the main plate or bridges.
anglage – angled finish of main plate or bridge edges, typically at a 45 degree angle. It is used to finish the movement, as well as to eliminate sharp corners that would otherwise be damaged while the watch is working.
shot blasting – a satin finish obtained by using tiny glass pellets, one or two microns in diameter.
physical vapor deposition – (PVD) method of coating watch cases by integrating titanium particles and then depositing gold for color. Generally comes in black finish, but other colors can be created. (Very similar to “titanium carbide”.)
diamond like coating – (DLC) a metal coating that produces a grey/black finish that is very scratch resistant and corrosion resistant. This type of coating is like PVD, but even harder (and more expensive).
sunray brushing – brushed finish that is typically used on metal components that results in a pattern of lines the intersect at a central point.
sunburst – a dial finish obtained by brushing the surface with an abrasive paste to create rays spreading from the center to the rim.
grand tapisserie – a type of guilloche-work that uses a machine with a burin to chisel lozenges between the squares on Audemars Piguet Royal Oak timepieces.



stem – the shaft that connects to the movement’s winding mechanism, the crown is fitted to the opposite end.
bridge – attached to the bottom plate to hold components in place. Fixed to the main plate to form the frame of a watch.
shock absorbers – spring devices in balance wheel bearings that divert shocks away from the fragile pivot to the sturdier parts of the balance staff. The springs allow the balance wheel to return to its original position after shocks.
rotor – part of an automatic watch that winds the mainspring. A flat piece of metal swivels on a pivot with the motion of the wrist. Its rotation continually winds the mainspring of the watch. It turns freely in both directions and uses the force of gravity to wind the mainspring.
pinion – small toothed wheel usually made of steel with a small number of teeth that mesh with gear train wheels.
pallets – typically made of synthetic rubies, meshes with the teeth of the escapement wheel and transmits an impulse to the balance.
balance spring – (same as “hairspring”) is one of the most important components of a mechanical timepiece. The balance spring is a fine spiral torsion used in mechanical wristwatches to control the rate of oscillation of the balance wheel, and thus the rate of the movement of the hands and accuracy of the timepiece. It is an integral part of the balance wheel, because it reverses the direction of the balance wheel causing it to oscillate to-and-fro (back-and-fourth). Considered the heart of a mechanical timepiece.
balance wheel – regulating organ of the watch, vibrating on a spiral hairspring. Lengthening and shortening of the balance spring makes the balance wheel go faster or slower to advance or retard the watch.
barrel – cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.
bezel – the ring around the top of the crystal. Generally hold the glass or crystal in place. A rotating ratchet bezel moves in some watches as part of a complication. Rotating bezels either rotate clockwise (uni-directional) or both counter-clockwise and clockwise (bi-directional) to assist in calculations.
crown – knob used to wind a mechanical watch and to set the time and/or calendar of a watch.
dial – face of the watch that generally displays hours, minutes, and seconds.
mainplate – (or “baseplate”) the plate on which all other parts of a watch movement are mounted. metal piece that holds up the bridge and other parts of the movement. The bottom side is the dial side the top side is the bridge side. supports the bridges, which are often on the top of the plate, the movement, the dial, and the holes where the jewels are inserted.
mainspring – this spring’s tension controls the amount of energy transmitted to the measurement. Hooked to the barrel and arbor, when it is tensed it releases energy. The driving flat-coiled spring of a watch contained in the barrel or barrels that supplies power. This is what is wound, by hand or via an oscillating weight, and then unwound to power a watch.
flange – ring that separates the crystal from the dial.
escapement – mechanism made up of the escapement wheel, lever, and discharging roller, which act to control the wheel movement and to provide pulses to pallets and thus the balance. Converts the energy of the mainspring into equal units of time. The escapement controls the amount of power released from the mainspring. The regularity is controlled by the balance and it’s spring. The escapement controls the rotation of the wheels and thus the motion of the hands. It is fitted at the end of the gear train and is designed to interrupt the movement of the wheels at regular intervals. (The escapement is the source of the ticking sound in watches and clocks.)
watch hands – watches generally have three hands for seconds, minutes, and hours. They come in many different shapes: Pear, Breguet, Baton, Arrow, Skeleton, Luminous, Alpha, Dauphine and more.
jewels – (also called “rubies”) synthetic sapphires or rubies that are used in a watch movement to reduce friction. They help maintain the watch’s lubrication. More jewels does not necessarily denote higher quality.
lug – (same as “horn”) part of case where bracelet or strap is attached.
spring bar – a spring loaded metal bar mounted between the case lugs used to attach the strap or bracelet.
arbor – the shafts that the wheels and pinions are mounted on.
sapphire crystal – synthetic corundum crystal with a hardness second only to a diamond. Transparent sapphire is used for a scratchproof watch glass. Made of crystallizing aluminum oxide at very high temperatures. Chemically the same as natural sapphire, but colorless. It is hard and brittle so it shatters easier than plexiglass or mineral glass. 9 on a mohs scale, a diamond is 10.
fusee – grooved pulley that equalizes the mainspring by controlling its winding or unwinding.
gasket – most water resistant watches are equipped with gaskets to seal the caseback, crystal, and crown from water. Gaskets need to be checked every couple of years to maintain water resistance.