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The specialist words used by watch manufacturers can be confusing when deciding which watch to buy. Our simple A to Z guide takes you through the most common watch words and explains what each one means

A

Analogue A watch that shows the time using hour and minute hands.
Atmosphere (ATM) This term is a measure of the water resistance of a watch. One atmosphere is equal to 10 meters of water.
Automatic winding This term refers to a watch with a mechanical movement (as opposed to a quartz or electrical movement). A rotor that turns in response to motion winds the watch’s mainspring. If an automatic watch is not worn for a day or two, it will wind down and need to be wound by hand to get it started again.

B

Battery reserve indicator Some battery operated watches have a feature that indicates when the battery is approaching the end of its life.
Bezel The ring that surrounds the watch dial.
Bi-directional rotating bezel A bezel that can be rotated either clockwise or counter-clockwise. These are used for calculations in sports and sailing watches such as average speed or distance, or for keeping track of elapsed time.

C

Calibre This refers to the size and type of a design of mechanical movement within a watch. Some watch manufacturers name their calibres or give them numbers to identify the type of movement.
Chapter ring The ring on the watch dial bearing figures and minute marks. The hour figures are sometimes called chapters.
Chronograph A watch that includes a built in stopwatch function such as a timer that can be started and stopped to time an event.
Chronometer For a Swiss made watch to be called a chronometer, it must meet certain very high standards set by the Swiss Official Chronometer Control (C.O.S.C.). If you have a Swiss watch labelled as a chronometer, you can be certain that it has a mechanical movement of the very highest quality.
Complications One or more features added to a watch in addition to its usual time-telling functions. Complications include perpetual calendars, moonphase displays, alarms, repeating mechanisms, quarter strikes as well as stop/start chronograph functions. Power reserve indicators are also usually regarded as complications.
Crown A crown is the button on the outside of the watch case that is used to set the time and date.
Crystal The transparent cover on a watch face made of glass crystal, synthetic sapphire or plastic. Better watches often have a sapphire crystal, which is highly resistant to scratching or shattering.

D

Dual time zone A watch that can display two time zones at the same time by a subdial or an extra hand.
Deployment buckle A type of clasp that can fold under the strap of the watch.

E

Escapement A device in a mechanical movement that controls the rotation of the wheels and the motion of the hands.

F

Flyback hand A seconds hand on a chronograph that can be used to time laps or to determine finishing times for several competitors in a race. Start the chronograph, putting both the flyback hand and the regular chronograph seconds hand in motion. To record a lap time or finishing time, stop the flyback hand. After recording the time, push a button and the hand will “fly back” to catch up with the constantly moving elapsed-time hand. Repeat the process to record as many lap times or finishing times as needed.

G

Gear train The system of gears that transmits power from the mainspring to the escapement.
Grande complications The most complex of mechanical watches featuring an abundance of complications.

J

Jewels Synthetic sapphires or rubies that act as bearings for gears in a mechanical watch. The jewels reduce friction to make the watch more accurate and longer lasting. Most watches with mechanical movements will contain at least 17 jewels.
Jumping hours A digital display where the time in hours is shown in the dial as a number, usually visible through a window. The number changes, or jumps, precisely on every hour.

K

Kinetic Technology developed by Seiko where the movement of your wrist charges a very efficient capacitor that powers a quartz movement.

L

Lugs These are the projections on the side of a case to which the watch strap or bracelet is attached with pin springs.

M

Mechanical movement A movement powered by a mainspring, working in conjunction with a balance wheel.
Minute repeater A complication within a watch that can chime the hours, quarter hours and minutes since the last quarter hour on small gongs inside the watch.
Moonphase display A graphic display by means of a specially shaped window in the dial to indicate the phase of the moon.

P

Perpetual calendar A calendar mechanism in a watch that displays the date correctly ‘perpetually’, taking into account the different lengths of the months as well as leap year’s day. The internal mechanism will move the dial to the next day.

Q

Quartz movement A movement powered by a quartz crystal. Quartz crystals are very accurate. They can be mass-produced which makes them less expensive than most mechanical movements that require a higher degree of craftsmanship.

R

Rotor The part of an automatic (or self-winding) mechanical watch that winds the movement’s mainspring. It is a flat piece of metal, usually shaped like a semicircle that swivels on a pivot with the motion of the wearer’s arm.

S

Skeleton watch A watch with no dial and only a chapter ring. As much metal is removed as possible to allow the wearer to see the mechanical movement within.
Solar powered A watch that uses solar energy (from any light source) to power the quartz movement.

T

Tachymeter A feature found on some chronograph watches, a tachymeter measures the speed at which the wearer has travelled over a measured distance.
Tonneau A watch that is shaped like a barrel, with two convex sides.
Tourbillon A device, invented by Breguet in 1801, in which the escapement is mounted in a small revolving cage as a means of overcoming the effects of gravity on the precision on a mechanical timepiece.

U

Uni-directional rotating bezel An elapsed time rotating bezel often found on divers’ watches, that moves only in a counterclockwise direction. Because the bezel moves in only one direction, the diver can err only on the side of safety when timing his dive. Many divers’ watches are ratcheted, so that they lock into place for greater safety.

W

Water resistance The ability to withstand splashes of water. Terms such as “water resistant to 50 meters” or “water resistant to 200 meters” indicate that the watch can be worn underwater to various depths.
World time dial A dial, usually on the outer edge of the dial, that tells the time in up to 24 time zones around the world.

Y

Yacht timer A countdown timer that sounds warning signals during the countdown to a boat race.