ATM (atmosphere) Unit of pressure used in watch making to indicate water resistance. CALIBER Describes the dimensions and configuration of the movement. CASE The metal housing of a watch’s parts, including movement, dial and crystal. CHRONOGRAPH A watch that includes a built-in stopwatch function. Most chronographs have two or three sub-dials for measuring hours, minutes and seconds. The timer counting seconds that can be started and stopped to precisely time an event.
CHRONOMETER A very high-precision watch. According to the Swiss law, a manufacturer may only put the word “chronometer” on a model if the watch meets very high standards, and after each individual piece has passed a series of tests and obtained a running bulletin and a chronometer certificate by an acknowledged Swiss control authority, such as the COSC.
CLASP The attachment used to connect the two ends of the watch strap or bracelet around the wrist.
CROWN The knob, or button, on the outside of the watch case that is used to set the time and date. It is also called a stem or pin. In a mechanical watch the crown winds the mainspring. A screw-in (or screw-down) crown is used to make a watch more water resistant.
CRYSTAL The protective cover over the watch face. Could be acrylic crystal, mineral crystal or sapphire crystal. Acrylic crystal is plastic and scratches easily. Mineral crystal is comprised of several elements, heat-treated for hardness and extra durability. Sapphire crystal is the most durable and most expensive.
DIAL Face of a watch, on which time and further functions are displayed by markers, hands, discs or through windows.
DIGITAL WATCH A watch that shows the time through digits, rather than a dial and hands.
DIVERS WATCH A watch that is water resistant to 200M, has a one-way rotating bezel and a screw-on crown and back, has a metal bracelet or rubber strap.
DUAL TIME ZONE A watch that displays two time zones, to simultaneously keep track of local time and time in another country.
FLYBACK CHRONOGRAPH A feature combined with chronograph functions that allows for a new measurement starting from zero by pressing down a single pusher, without stopping, zeroing and restarting the whole mechanism.
FOLD-OVER CLASP Hinged and jointed element, normally of the same material as the one used for the case. It allows easy fastening of the bracelet on the wrist.
GMT Greenwich Mean Time. As a feature of watches, it means that two or more time zones are displayed.
GUILLOCHE Decoration of dials, rotors or case parts consisting of patterns made by hand or engine-turned. By the thin pattern of the resulting engravings & consisting of crossing or interlaced lines.
HAND Indicator for the analog visualization of hours, minutes, and seconds as well as other functions.
HELIUM VALVE Valve inserted in the case of some professional diving watches to discharge the helium contained in the air mixture inhaled by divers.
HOROLOGY The science of time measurement, including the art of designing and constructing timepieces.
JEWELS Synthetic sapphires or rubies that are used as bearings for gears in a mechanical watch. The jewels reduce friction to make the watch more accurate and longer lasting.
JUMPING HOUR Feature concerning the digital display of time in a window. The indication changes almost instantaneously at every hour.
LUG Double extension of the case middle by which a strap or bracelet is attached.
LUMINESCENT Materials applied on hour markers or hands, emitting the luminous energy previously absorbed as electromagnetic light rays.
MAINSPRING Together with the barrel, makes up the driving element of a movement. It stores and transmits the power force needed for its functioning.
MANUAL MOVEMENT A mechanical in which winding is performed by hand. The motion transmitted from the user’s fingers to the crown is forwarded to the movement through the winding stem to the barrel, through a series of gears to the mainspring.
MARKERS Elements printed or applied on the dial, sometimes they are luminescent, used as reference points for the hands to indicate hours and minute intervals.
MECHANICAL MOVEMENT A movement powered by a mainspring, working in conjunction with a balance wheel.
MINERAL CRYSTAL Mineral crystal is comprised of several elements, heat-treated for hardness and extra durability.
MINUTE REPEATER Mechanism indicating time by acoustic sounds. Contrary to the watches provided with en-passant sonnerie devices that strike the number of hours automatically, repeaters work on demand by actuating a slide or pusher positioned on the case side. Repeaters typically have two hammers and two gongs, one for minutes and one for hours. Quarters are indicated by the simultaneous strike of both hammers.
MOON PHASE An indicator that keeps track of the phases of the moon. A regular rotation of the moon around the earth is once every 29 days, 12 hours and 44 minutes.
MOVEMENT The entire mechanism of a watch. Movements are either quartz or mechanical manual or automatic winding devices.
OSCILLATION The travel of the balance wheel from one extreme to another, and back again.
POWER RESERVE The time a watch will run with a fully-charged power supply. Duration in hours of the residual functioning autonomy of a movement after it has reached the winding peak. The duration value is displayed by either an analog or digital instantaneous indicator. The related mechanism is made up of a series of gears linking the winding barrel and hand.
PUSHER Mechanical element mounted on a case for the control of specific functions.
QUARTZ MOVEMENT A movement powered by a quartz crystal that keeps very accurate time.
RETROGRADE Used to describe a pointer hand on a watch dial, which returns to zero at the end of a defined period.
ROTATING BEZEL A bezel that can be turned, sometimes both clockwise and counterclockwise.
ROTOR In automatic winding mechanical movements the rotor is the part that by its complete or partial revolutions and the movements of the arm, allows the winding of the mainspring.
SAPPHIRE CRYSTAL Sapphire crystal is the most durable, most scratch-proof and most expensive.
SCREW-IN or SCREW-DOWN CROWN A crown used to make a watch more water resistant. The seal is achieved by matching a threaded pipe in the case with the crown’s internal threads and creating a gasket while twisting the crown to lock it in place.
SHOCKPROOF or SHOCK-RESISTANT A watch with the ability to withstand a high impact.
SKELETON Watches whose bridges and pillar plates are cut out in a decorative manner, thus revealing all the parts of the movement.
SPLIT-SECOND CHRONOGRAPH Additional hand superimposed on the chronograph hand, used for timing simultaneous events that begin at the same time and end at different times.
STOPWATCH A watch with a second hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, it is referred to as a chronograph.
SUBDIAL A small additional dial or indicator that may be positioned or placed off-center on the main dial, used for the display of various functions.
SWEEP SECOND HAND A center second hand mounted on the center of the main dial.
TACHOMETER or TACHYMETER Function that measures the speed at which the wearer has traveled over a given distance. The scale is calibrated to show the speed of a moving object over a known distance. The standard length on which the calibration is based is shown on the dial - ex: 100, 200 or 1,000 meters.
TONNEAU Barrel shaped watch case with straight, shorter, horizontal sides and curved, longer, vertical sides.
TOURBILLION The function that equalizes position errors due to changing positions of a watch, and related effects of gravity, to ensure accuracy. The round carriage of the tourbillion holds the mechanisms that rotate the wheels, and thus the hands of the watch, at a continuous rate of once per minute.
WATER RESISTANT or WATERPROOF A watch whose case is designed to resist infiltration by water.
WINDING STEM Element transmitting motion from the crown to the gears governing manual winding and setting.
WORLD TIMER Additional feature of a watch with GMT function, displaying the 24 time zones on the dial or bezel, each referenced by a city name, providing instantaneous reading of the time in any country.