GLOSSARY OF WATCH TERMS

A

A/h

Half-oscillations (also known as "beats" or "vibrations") per hour. Two half-oscillations produce the familiar "tick-tock" of a mechanical watch. Together, two beats comprise one oscillation.

Analog

The display of time that is indicated visually by comparing the movement of hands in relation to a fixed scale (on the dial).

Analog - Digital

This is a watch that has both hands and a digital display in numbers.

Aperture

An opening in the dial of the watch that displays various information such as the date.

Ardillon Buckle

Similar to a regular belt buckle. See Tang-Type Buckle.

Atmosphere (ATM)

A measure of the water resistance of a watch. An ATM is equal to 10M of water pressure.

Automatic Movement

An automatic watch has a mechanical movement and does not need to be regularly wound. Its power comes from the movement of an oscillating weight (rotor) which rotates as you move your arm as you are wearing the watch. The rotor tightens the mainspring which creates energy for the watch to function.

B

Balance

The Balance works in combination with the balance-spring to regulate the rate of a mechanical watch.

Balance Wheel

The regulating organ of a watch with a mechanical movement that vibrates on a spiral hairspring. Lengthening or shortening the balance spring makes the balance wheel go faster or slower. The travel of the balance wheel from one extreme to the other and back again is called oscillation.

Battery Reserve Indicator

Some Quartz watches have this function. The watch will indicate when the battery is nearing the end of its life. This can often be seen by observing the movement of the hands which will jump 2-4 seconds depending upon the make and model.

Bearings

Holes drilled to accept the pivots of the gear-train.

Bezel

The Bezel is the surface ring of metal which surrounds the dial of the watch and holds the crystal securely in place. Often it serves functions such as a timing device or assisting in various calculations. Bezels can be fixed (stationery), uni-directional (rotating in one direction only) or bi-directional (rotating in both directions.)

Bi-Directional Bezel

A bezel which can turn both clockwise or counter-clockwise and acts as a timing device or assists in performing various calculations.

Blued Hands

Bluing occurs when the surface of a steel component oxidizes upon exposure to heat.

Bracelet

A metal band used to secure the watch to your wrist usually made of joined, flexible links. You can change the length by removing or adding links. (Also see Strap.)

Brushed Steel

Stainless Steel with a Matt 'brushed' effect finish.

Buckle

A device which joins both ends of a strap or bracelet together and is often made of the same material as the case of the watch. A tang-type buckle has a tongue which fits in holes on the opposite side of the strap (similar to a belt buckle). A Deployment buckle is one that folds onto itself and locks into place.

C

Cabochon

A type of cut for a precious stone which is polished into a rounded shape but lacking facets.

Cadrature

An auxilary mechanism, usually located directly beneath the dial, to support with watch's chimes, calendar functions or chronograph functions.

Calendar

Date Indicator

Caliber

Technical term denoting the type and dimensions of a movement. It is expressed as a number or in millimeters or lines, the old unit of measurement equivalent to 2.256mm.

Carat

A unit of measurement specifying the amount of gold in an alloy. The Carat Scale ranges from 0 to 24. Fine gold, which is nearly 100% pure, is described as 24 carat. 18K gold is made of 750 parts per thousand of fine gold.

Case

The metal housing which holds the internal parts of a watch. The dimensions given for the size of a watch are measured from the outside of the case (9:00) to the opposite side (3:00), not including the crown.

Chronograph

A watch with 3 subdials within the larger dial. Used to measure short time periods such as with a stopwatch.

Chronometer

A Standard set by the Official Watch Institute of Switzerland (COSC). The watch would have been rigorously tested for its accuracy at various temperatures and in different atmospheres and is supplied with a certificate.

Clasp

A device which joins both ends of a bracelet or strap together and is often made of the same material as the case of the watch. A Deployment clasp is a buckle that folds onto itself and locks into place.

Co-Axial

An escapement invented by Dr. G. Daniels which uses a low-friction energy transmission system.

Cocks

Cocks are fitted with bearings in which the lever, balance or wheels pivot. A cock is affixed at only one point by means of so-called "feet."

Corrector

Manual correction function for a specific element.

Cosmograph

As with a Chronograph, except that the Tachymeter function is found on the bezel of the watch.

Crown

The crown is the button on the side of the watch (usually the right) which changes the time and date of the watch. The Crown is also used to wind the watch depending on its movement. Many watches have crowns that screw down for a better watertight seal.

Crystal

The clear cover over the dial and hands of a watch which can be made of: (1)Acrylic Crystal which allows shallow scratches to be buffed out, (2)Mineral Crystal which is heat-treated to help resist scratches and (3)Sapphire Crystal which is the most expensive and durable. Sapphire Crystal is approximately 3 times harder than mineral and 20 times harder than acrylic crystals.

D

Date Jumper

Systems and concepts with an effect on the date change at midnight. These consist of: (1)Instantaneous - the date changes at midnight, (2)Semi-instantaneous - the date moves slowly from around 11:30pm, and (3)Dragging - the date changes slowly, starting around 11:00pm.

Deployment Buckle

A Deployment buckle is one that folds onto itself and locks into place.

Dial

The "face" of the watch that contains the numerals, indices or surface design used for reading the time or displaying other information. Subdials are smaller dials that can be set into the main dial and indicate chronograph or other functions or displays.

Digital Display

The watch display that is indicated digitally by using means of an LCD: Liquid Crystal Display or LED: Light-Emitting Diode.

Diver's Clasp

A special expandable clasp designed to be able to wear over a diving suit

Domed Crystal

A convex pane of transparent material covering a watch's dial.

Dual Time Zone

A watch that displays 2 different time zones by means of a Subdial, an extra hand etc.

E

Enamel

A colored or transparent layer of vitreous material (i.e. a special type of glass) which protects or decorates its metal substrate.

End of Life (EOL)

Indicates the end of life of a battery within a quartz watch by succesive jumps of the seconds hand of 4 seconds or a flashing digital display.

Engine-Turning

The engraving of interwoven geometric forms (guilloché) onto a metal surface which is accomplished mechanically by an artisan who guides an engraving tool equipped with various mechanical gears.

Escapement

The part of the watch that restricts the electrical or mechanical impulses of the gear train, metering out the passage of time into equal, regular parts.

F

Frequency

The number of vibrations (half-oscillations) per second, in hertz (Hz).

Flyback hand

A seconds hand on a chronograph that is used to time the duration of two or more sequences such as determining lap or finishing times. It works as follows: first push of the chrono button starts the seconds hand. Second push causes the seconds hand to reset to zero and begins. This is opposed to a normal chrono where you push once to start, once more to stop, and another button to return to zero, and once more to begin again. The purpose of the flyback is to begin retiming quickly.

G

Gear Train

A series of small gears in both quartz and mechanical movement watches that are responsible for transmitting the power from the battery (in a quartz watch) or spring (in a mechanical watch) to the escapement, which distributes the impulses to mark the time.

GMT

Greenwich Mean Time, used as universal standard time.

Gold

Gold is a precious metal that is used as with an alloy frequently in watch making. The amount of gold is measured in Carats.

Guilloché

An ornamental pattern on a Dial. As opposed to a flat colour, a Guilloché dial is textured with a repeating pattern.

H

Hands

The pointing device anchored at the center and circling around the dial indicating hours, minutes, seconds and any other special features of the watch. There are many different types of hands:
Alpha: A hand that is slightly tapered.
Baton: A narrow hand sometimes referred to as a "stick hand".
Dauphine: A wide, tapered hand with a facet at the center running the length of the hand.
Skeleton: Cutout hands showing only the frame.
Luminous: Hands made of skeleton form with the opening filled with a luminous material.

Hand-wound

A timepiece whose mainspring must be wound daily my manually twisting it's crown.

Helium Escape Valve

Decompression System allowing helium to escape from inside the watch. Used professionally in decompression chambers.

Horology

The art and study of watch making.

I

Indication

Display, e.g. display of the time, date, full calendar, equation of time, or power reserve.

Inhibition

Electronic process for adjusting a quartz watch without modifying the frequency of the quartz.

J

Jewels

The international designation for the rubies or other stones in a watch-movement. Within a mechanical watch the jewels are used as bearings. Most watches with mechanical movements will contain at least 17 jewels.

Jumping Hours

Function allowing digital displays of the hours in a window at 12 o'clock and the display of minutes by a hand. Each revolution of the minutes hand triggers an immediate jump in the hour window.

K

Kinetic

Kinetic watches run entirely on generated energy from natural movement of your wrist. It does not require a battery.

L

LCD

Liquid-crystal display. A digital time display used to give additional chronograph indications.

Lugs

The narrow ends on the sides of the case where the bracelet or strap is joined.

Luminous

Illuminating substance on the batons, numerals and/or hands of certain watches.

M

Mainspring

A coiled spring which is the energy source responsible for powering the watch movement (as opposed to a battery). The spring is wound, either manually (using the winding stem) or automatically (by the motion of the wearer's wrist.) Potential energy is stored in the coiled spring, and then released to the gear train, which transmits the power to the escapement and motion work, which turns the hands on the watch dial.

Manual

A hand-wound mechanical watch.

Mechanical

Describes a watch movement with a balance wheel.

Mechanical Movement

A movement based on a mainspring which is wound by hand; when wound, it slowly unwinds the spring in an even motion. An automatic mechanical requires no winding because of the rotor, which winds the mainspring every time you move your arm.

Military or 24-hour time

When time is measured in 24-hour segments. To convert 12-hour time into 24-hour time, simply add 12 to any p.m. time. To convert 24-hour time into 12-hour time, subtract 12 from any time from 13 to 24.

Mineral Crystal

Watch glass that has been tempered to increase its scratch resistance. Mineral Crystal is harder than plexiglas, but softer than sapphire crystal. Mineral Crystal has a scale of 5 on the Moh's scale of a hardness.

Minute Repeater

A complication on a watch that can strike the time in hours, quarters, or seconds by means of a push piece.

Moon Phase

A rotating disc beneath and aperature in the dial that keeps track of the phases of the moon. A regular rotation of the moon is once around the earth every 29 days, 12 hours, and 44 minutes. once set, the moon phase indicator accurately displays the phase of the moon.

Mother-of-Pearl

Iridescent, milky interior shell of the fresh water mollusk that is sliced thin and used on watch dials. While most have a milky white luster, mother-of-pearl also comes in other colors such as silvery gray, gray blue, pink, and salmon.

Motion Work

A series of parts inside a watch that receive power from the escapement and gear train, which distribute and generate the watch's power. The motion work is responsible for actually turning the watch's hands.

Movement

The inner workings or assembly that make up the main timekeeping mechanism. Movements are either quartz or mechanical (automatic or hand-wound). This is the "engine" of the watch.

Multifunction

Watch with digital (or combined analog/digital) display with several functions such as alarm, chronograph, countdown timer, etc. with optional display of the required mode.

N

O

Oscillation

The travel of the balance wheel from one extreme to the other and back again.

Oyster

Invented in 1926 by Rolex. At the time it was described as" the first waterproof, airtight and dustproof watch. It was named Oyster due to its shape. Rolex displayed the new Oyster watch by submerging the watch in an aquarium and placing it in the windows of watch shops.

P

Perpetual

A perpetual rotor converts the movement of the wrist into energy that can be stored in and powers the watch.

Perpetual Calendar

Memory function that respects all date changes, including 29th February in leap years.

Pink Gold (Also Rose Gold)

Gold combined with an alloy such as copper with creats a "pink" or "rose" tint

Platinum

A very rare and costly precious metal. Most platinum is used in a very pure alloy (950) which contains 950 parts platinum per 1,000 parts (i.e. 95% pure platinum). A platinum watch-case weighs about 35% more than a corresponding case made of 18K Gold.

Polished

A metal, usually Stainless Steel, which has been smoothed to a shiny finish. (As opposed to Brushed)

Power Reserve

Maximum interval during which a mechanical movement continues to run after it's mainspring has been fully wound. Watches may have a Power Reserve Indicator on the dial of the watch to indicate the amount of power left.

Push-Piece

A component which activates or deactivates a particular function. (i.e. The stopwatch functions of a chronograph are started, stopped and returned to zero by means of a push-piece.

Q

Quartz

A watch which is powered by a series of electronic components using a battery as the energy source. The battery sends electrical energy to a rotor to produce an electrical current.The current passes through a magnetic coil to a quartz crystal, which vibrates at a very high frequency (32,768 times a second), providing highly accurate timekeeping. These impulses are passed through a stepping motor that turns the electrical energy into the mechanical energy needed to turn the gear train.

R

Rapid Adjustment

(For time display in a second time zone.) A mechanism which enables the user to directly adjust the indicator of the time in a second time zone through increments of one hour by means of a push-piece.

Rattrapante (Split Seconds)

A chronograph function with 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 catchup with the moving seconds.

Regulator

Precision pendulum clock which was formerly used to test smaller timepieces.

Retrograde

A hand moves to indicate something (e.g. the hour or the date) along a segment of a circle. When the hand reaches the end of the calibrated scale, it rapidly jumps back to its original position and resumes its forward motion.

Rotating Bezel

A bezel that can be turned. Different types of rotating bezels perform different functions.

Rotor

An oscillating mass which turns freely and without restriction about its own axis inside an automatic watch. Depending on the construction of the self-winding mechanism, the mainspring can be tightened by the motion of the rotor in either one or both directions of rotation. There are central rotors as well as off-center rotors (also known as "microrotors" or "planetary rotors".) Central rotors turn beneath and across the full disk of the movement; off-center rotors are integrated within the plane of the movement.

S

Sapphire Crystal

A transparent crystal frequently used in watch making due to its resistance to scratching. Sapphire Crystal has a scale of 9 on the Moh's scale of a hardness.

Sapphire Crystal Caseback

A watch which has a transparent caseback, usually sapphire crystal, that allows you to see the inner workings of the watch movement.

Scratch-Resistance (See Crystal)

The ability of the watch crystal to deflect scratches on it's surface. The sapphire crystal has the most scratch-resistance of all the current available crystals.

Screw-Locking Crown (Also Screw-in Crown)

The screw-in crown seals the crown against the case and aids in water resistance.

Skeletonized Movement

A watch-movement whose plates, bridges, cocks, barrel (and sometimes also) rotor have been punched, sawn or milled to create fretwork, leaving behind only as much material as is absolutely necessary for the organ to perform its appointed task. A Skeletonized Movement is an embodiment of the high art of watchmaking.

Split Seconds (Rattrapante)

A chronograph function with 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 catchup with the moving seconds.

Stainless Steel

A metal alloy of steel, nickel and chrome which is known for its resistance to rusting. The most common metal used in watch making.

Stop Seconds (Function)

A braking system on the balance-spring with allows the seconds hand to be synchronized when the time is set (crown in position 3).

Strap

A band used to secure the watch to your wrist. It is usually made of leather, rubber, canvas, plastic, etc.

Subdial(s)

A smaller dial within the face on a Chronograph to display other functions, such as time elapsed.

Sun/Moon Indicator

A wheel visible on the dial of a watch displaying the sun and moon over a 24 hour period.

Swiss Lever Escapement

A detached escapement for small timepieces in which the teeth of the escape-wheel widen like wedges as they progress outwards, thus distributing the lift on the escape-wheel and the lever with its two jeweled pallets.

T

Tachymeter

Often used in the motor industry to measure the speed of a car over a specific distance. Functions via a scale on the bezel of a chronograph. Average speeds or hourly production rates can be calculated over a period of observation of less than 60 seconds. To measure the speed, a standardized distane of one kilometer or one mile must be traversed. At the start of the standard stretch, the chronograph function is switched on. When the wearer reaches the end of the measured distance, the chronograph function is switched off. The chronograph's hand then points to the average speed in km/h or mph with which the standard distance has been traversed.

Tang-Type Buckle

The more commonly recognized buckle. It is similar to a regular belt buckle. It consists of a metal loop through which the strap is inserted through and a tongue which is inserted into various holes in the strap according to size needed.

Titanium

A stronger and lighter metal than Stainless Steel. It is increasingly being used to make watches.

Tourbillon

All the components of the escapement (escape wheel, pallets wheel, pallets fork and balance spring) are grouped together ina small mobile cage which makes one rotation per minute. This eradicates any differences in rate due to different positions of the watch and thus guarantees optimal precision for a mechanical watch.

Triple Date

A complete calendar showing the current day, date and month.

U

Uni-Directional Bezel

A bezel which can turn in one direction and generally acts as a timing device.

V

W

Waterproof

Beware if a watch is described as waterproof as this would not be the case. No watch is considered 100% Waterproof and watches are not allowed to be termed as such. (See Water Resistant for correct terminology.)

Water Resistance

Water resistance is the amount of measurement given to indicate the depth to which it can withstand pressure. The amount of water resistance will determine what type of activity the watch can withstand. Some typical guidelines are listed below:
Water Resistant - light rain or hand washing, but should not be used while swimming or diving.
Water Resistant to 50M (165Ft.) - Suitable for showering or shallow water swimming
Water Resistant to 100M (330Ft.) - Suitable for swimming or snorkeling.
Water Resistant to 150M (500Ft.) - Suitable for snorkeling.
Water Resistant to 200M (660Ft.) - Suitable for skin diving.
Sometimes water-resistance is measured in atmospheres (ATM). An ATM is equal to 10M of water pressure.
Note: Be careful with cleaning materials. Certain chemicals can cause the rubber seal inside the crown to deteriorate and thereby cause the watch to lose it's water resistance.

White Gold

A precious metal which is an alloy of yellow gold with nickel or similar metal. It is available in 14K or 18K.

X

Y

Yellow Gold

A precious metal which is either 14k or 18k. The traditional gold used in watch making in both all gold or bi-metal combinations.

Z