Watch Glossary

A sub-dial on a chronograph that can record time periods of up to 12 hours.

A sub-dial on a chronograph that can record time periods of up to 30 minutes.

Sometimes referred to as Hesolite, an acrylic crystal is made up of plastic composite that is generally less expensive and less durable than a sapphire or a mineral crystal. It's flexible, malleable make up means it will not shatter on impact. It also produces fewer glares under bright lights and can be easily polished.

A device that makes an alerting sound at a preset time. Alarm watches can be either quartz or mechanical.

A function, commonly found in pilot watches or inside a pressurized airplane cabin, that shows altitude by responding to changes in barometric pressure.

A watch that has a dial, hands, numbers, or other types of markers that present a total display of 12 hours.

A watch that shows the time by means of hands (analog display) as well as numbers (digital display), usually found in sport watches. The analog display has a traditional dial with hour, minute, and sometimes seconds hands. The digital display shows the time in Arabic numerals with a liquid crystal display.

A watch showing the day, date, month, and 24 hours, adjusting automatically for short and long months. The calendar needs setting only once a year between the end of February and the first of March.

Small openings carved into the watch that display certain indications, such as the date or hour. Some apertures may only be visible when the watch dials are in certain positions.

Measures the normal pressure of the air at sea level. It is used in watchmaking to indicate water-resistance.

Makes allowances for months of different lengths, and leap years. Some are pre-programmed until 2039.

Currently, the most accurate timekeeping devices on earth. These are accurate to 1 second in 1,400,000 years. This information is broadcast throughout the day from a radio transmitter in Ft. Collins, Colorado.

Provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division in Boulder, Colorado, atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America, enabling some atomic watches to correct themselves to the exact time.

A feature that causes the watch to update daily, using a radio signal broadcast from Ft. Collins, Colorado. All that needs to be set is the time zone.

Mechanically powered by the motion of the wearer's arm rather than by turning the winding stem. In response to this motion, a rotor turns and winds the watch's mainspring so that it keeps accurate time. Most automatic watches have up to 36 hours of power reserve. If an automatic watch is not worn for a day or two, it will need to be wound by hand to restart again.

When turned on, the backlight illuminates when you turn your wrist toward your face.

Measures the distance between the case lugs. Therefore, band width may not necessarily be the exact width of the watch band, as a bracelet or strap can have tapering widths. When swapping watch bands or purchasing replacement bands, the band width of the new band must match the distance between the case lugs.

A function that signals an impending battery failure in a Quartz watch by means of the second hand jumping in two- or four-second intervals. The watch has approximately two weeks before battery failure.

A watch that uses hybrid technology to run without manual winding. These timepieces use movement powered from a small, electrical generator. Energy is stored in a rechargeable battery or similar device in order to keep the watch running properly. Commonly known under proprietary names such as Kinetic (Seiko), Omega-matic (Omega), and Auto Quartz (Invicta), battery-less quartz watches function like automatic watches and must be worn regularly to maintain their electrical power reserve.

Generically, the upper part of the watch body. Specifically, it usually refers to a ring that goes around the outside of the crystal. On jewelry watches, for instance, the bezel may contain a ring of diamonds. On sports watches, the bezel may show calibrated markings and have the ability to rotate in one or two directions.

A bezel that can be moved either clockwise or counterclockwise, usually used for mathematical calculations or keeping track of elapsed time.

The acronym for the Contr?le Officiel Suisse des Chronom?tres (the Official Swiss Chronometer Testing Institute), the institute responsible for certifying the accuracy and precision of wrist watches in the country of Switzerland. A C.O.S.C. certified timepiece can be identified by a serial number that is engraved in the movement, and an additional certification number provided by the institute.

Decorative in its purpose, indicates a smooth round or oval convex-shaped polished gemstone set in the watch crown.

Refers to the metal housing that contains the internal parts of a watch. Most cases are made up of stainless steel, but titanium, gold, silver, and platinum are also used.

An approximate watch measurement from one end of the watch to the other that does not include the crown.

The thickness of the watch, measured from the highest point of the crystal to the base of the watch case.

A multifunction sport watch with a stopwatch function. Most have two or three sub-dials or mini dials for measuring minutes and hours. When used in conjunction with specialized scales on the watch dial, it can perform many different functions, such as determining speed or distance (see tachometer and telemeter). Some chronographs can time more than one event simultaneously (see fly back hand and split seconds hand).

A fly back hand (rattrapante) on a watch, making it possible to measure split-seconds of time or simultaneous events of unequal durations.

This term refers to a precision watch that is tested in various temperatures and positions, thus meeting the accuracy standards set by C.O.S.C. in Switzerland. These watches are provided with a chronometer certificate detailing specific test results.

Additional features beyond the simple display of hours, minutes, and seconds on a wrist watch. Features such as day-date displays, automatic movements, and chronographs do not necessarily label a watch as complicated. A watch that is complicated usually consists of more parts and, quite possibly, greater than a thousand parts. As a result, wrist watches with complications have a greater number of functions.

A function that lets the wearer monitor how many hours, minutes, or seconds have elapsed from a preset time. Some countdown timers sound a warning signal a few seconds before the time runs out. These are useful in sporting events, such as races.

Often referred to as the winding crown or winder, a knob used for winding a manual watch, setting the hands to the correct time, and setting the date in calendar-equipped watches. On diving or sport models, the crown may screw down onto a threaded tube, which protrudes from the watch case to better ensure superior water-resistance.

The covering of the watch dial. Acrylic, mineral, and sapphire are three types of crystals commonly used in watches. Acrylic crystal is an inexpensive plastic that allows shallow scratches to be buffed out. Mineral crystal is composed of several elements that are heat-treated to create an unusual hardness that helps resist scratches. Sapphire is the most expensive and durable crystal, approximately three times harder than mineral crystals and 20 times harder than acrylic crystals.

A caseback made of transparent material, such as hardened mineral or sapphire crystal, that reveals the intricate mechanical movements of the watch.

A small window or lens in the crystal that is added to magnify the date to two-and-a-half times for enhanced readability.

Sounds each day at preset time.

A deployment buckle, also known as a foldover, is a three-folding enclosure that secures the two ends of the bracelet allowing enough room for placing the watch on the wrist when fully deployed. When closed, the buckle covers the two-piece folding mechanism.

Divers wear depth alarm watches that sound when the wearer exceeds a preset depth level. In most watches, the alarm stops sounding when the diver ascends above the preset level.

Divers wear depth sensor or depth meter watches to determine their depth level by measuring water pressure. Readings may be shown using analog hands and a scale on the dial or on a digital display.

A type of display that first appeared in the 1970s on wrist watches. Since then, digital watch technology has vastly improved, and continues to add on new and helpful features. In general, functions in digital watches work by push-buttons, either on the side of the watch case, or on the surface of the watch itself. Many kids' watches feature digital-displays, as well as sports watches.

Divers' watches traditionally feature a graduated rotating bezel, a screw-down winding crown, and a caseback; such watches must be water resistant to at least 200 meters (660 feet).

The term dual time refers to a watch that measures current local time as well as at least one other time zone. The additional time element may come from a twin dial, extra hand, sub dial, or other means. Another time keeping mode, to keep the time in another time zone. Also known as Worldtime.

A dual time/second time zone contains a rotating bezel, which can be used to display a separate time zone distinct from that shown on the dial.

Elapsed time refers to the actual amount of time it takes for an object to travel over a specified distance.

A graduated rotating bezel (see "rotating bezel") is used to keep track of designated periods of time. The bezel can be turned so the wearer can align the zero with the watch's seconds or minutes hand. The wearer can then read the elapsed time off the bezel instead of having to calculate the elapsed time.

Usually found in higher priced automatic or mechanical hand wind watches, an exhibition caseback provides a clear view of the intricate movements and parts of the inside of a watch. Rather than metal sitting on your wrist, a mineral or sapphire crystal replaces the base of the watch and allows for easy viewing.

Fishermen & Hunters have used the phases of the moon to predict the best time for fishing/hunting. These watches show moon age; time to fish/hunt, and sunrise/sunset based on set Latitude and Longitude.

A flyback hand is an additional hand on a chronograph watch that moves with the seconds hand, but can be stopped independently to measure a preset interval of time. It can then "fly back" to catch up with the seconds hand. This feature is useful for capturing lap times as well as finish times.

Greenwich Mean Time (GMT), also known as Zulu Time, is set to the international clock in Greenwich, England. Through an additional hour hand, it reflects the world time on a 24-hour scale and is used by pilots across the globe.

The application of gold over the surface of an item is called gold plating.

A hand winding watch with a manual mechanical movement needs to be wound regularly by the wearer using the winding crown in order to keep accurate time. This motion winds the mainspring, which then releases its energy to power the watch.

When turned on, watch beeps every hour on the hour.

Fishermen & Hunters have used the phases of the moon to predict the best time for fishing/hunting. These watches show moon age; time to fish/hunt, and sunrise/sunset based on set Latitude and Longitude.

A physical vapor deposition (PVD) process that is often applied to stainless steel watch cases and bracelets, allowing a break from the traditional silver-tone stainless steel color, by coating a darker, dark-grey to black compound to the surface of the steel. This process is used to deposit hard coatings of compound materials in wrist watches.

A karat is an indication of a metal?s purity, expressed as proportions of 1/24th of the pure metal used in the alloy. Metals such as gold are too soft in their pure state to use in jewelry, so they are typically made into an alloy for strength. 24K (equal to 24/24ths) is pure metal, and 18K is 18 parts pure metal mixed with 6 parts of other metals. That translates to 18/24=0.750, which is 75% pure or 750 parts per thousand.

Referring to the Seiko line of Kinetic watches, this innovative technology has a Quartz movement that does not use a battery. Movement of the wearer?s wrist charges a very efficient capacitor that powers the Quartz movement. Once the capacitor is fully charged, men?s models will store energy for 7-14 days without being worn and ladies? models will store energy for 3-7 days. The watch alerts the wearer to a low capacitor charge when the second hand starts to move in two-second intervals.

Some Quartz sport watches are built with a lap memory which enables the watch to store the times of laps in a race determined by the lap timer (see "lap timer"). The wearer can recall these times on a digital display by pushing a button. Allow you to store lap/split times into memory. With a watch with 10 lap memories, 10 are stored. If more than 10, the first 9 and last are stored.

A lap timer is a chronograph function that lets the wearer time segments of a race. At the end of a lap, the wearer stops the timer, which then returns to zero in order to begin timing the next lap.

The extensions on the top and bottom of a wrist watch, where the bracelet, strap or band is attached.

An LCD display shows the time electronically by means of a liquid held in a thin layer between two transparent plates. It follows from the earlier LED or Light Emitting Diode display of the first Quartz digital watches. The LCD is preferred as it uses vastly less power enabling the time to be shown constantly instead of only when pressing a display button.

A magnified window, also known as a cyclops, is a small window or lens in the crystal that magnifies the date two and a half times.

Manual winding refers to a watch with a manual mechanical movement, which needs to be wound by the winding crown. This motion winds the mainspring up which then releases its energy to power the watch.

A watch?s mechanical movement is based on a mainspring, which, slowly unwinds in a steady motion to provide accurate timekeeping. As opposed to a manual mechanical watch, which needs to be wound on a consistent basis, an automatic mechanical watch requires no winding because its rotor winds the mainspring when the wearer moves their wrist (see the section on automatic watch maintenance for more details).

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

Mineral crystal is made from what is essentially a form of glass. More scratch resistant than acrylic, a mineral crystal will scratch and is extremely difficult to polish.

A measure of a mineral's hardness and resistance to scratching, invented by Austrian mineralogist, Friedrich Moh. The scale ranges from talc, the softest, to diamonds, the hardest (talc = 1, gypsum = 2, calcite = 3, fluorite = 4, apatite = 5, feldspar = 6, quartz = 7, topaz = 8, corundum = 9, diamonds = 10). Most gemstones have a rating of 6 to 8. Sapphire crystals have a rating of 9, and mineral crystals have a rating of 6.

Displays phases of the moon, along with moon up and moon down time. Moon up is when it reaches the highest point in the sky relative to your current location; moon down is the lowest, usually on the other side of the Earth.

The moon phase is an indicator 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 refers to the iridescent milky interior shell of the freshwater 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.

Movement refers to the means by which a watch keeps time and often includes the power source. For example, a watch with mechanical movement uses a spinning balance wheel powered by a tightly wound spring. A watch with Quartz movement measures the vibrations in a piece of Quartz and often is powered by a battery.

Responding to the impact of the wearer's steps, a pedometer counts the number of strides a wearer takes.

A perpetual calendar adjusts automatically to account for different lengths of months (30 or 31 days) and leap years. Perpetual calendars, which can be powered by Quartz or mechanical movements, are programmed to be accurate until the year 2100.

A power reserve indicator is a feature that shows when the watch will need a new battery or winding. A battery reserve indicator on a Quartz watch informs the wearer when the battery is low. Often this is indicated by the second?s hand moving at two- or three-second intervals. Seiko's Kinetic watches are Quartz watches that do not have a battery (see Kinetic). When a Seiko Kinetic needs to be wound, the seconds hand will also move in two-second intervals.

A power reserve measures the amount of time a watch will run after being fully powered or wound, with no additional power input. Normally, a mechanical watch that is fully wound or a Quartz watch with a new battery has a full power reserve. Many modern mechanical watches have a power reserve of 40 hours. Power reserve also applies to battery-less Quartz watches, which may have power reserves from 40 hours to 6 months. On battery-operated Quartz watches, the term power reserve is sometimes used to refer to the expected battery life--typically 12 to 32 months.

A pulsimeter is the scale on a chronograph watch for measuring pulse rate.

The term push-piece refers to a button that is pressed to work a mechanism. Push-pieces are usually found on chronographs, striking watches, and alarms.

A Quartz is a caliber that uses the vibrations of a tiny crystal to maintain timing accuracy. The power comes from a battery that must be replaced about every 2-3 years. In recent years, new Quartz technology enables the watch to recharge itself without battery replacement. This power is generated via movement similar to an automatic mechanical watch, or powered by light through a solar cell (Kinetic & solar-tech).

A ratchet bezel ring can either turn one way (counter clockwise) or both ways and generally clicks into place.

The addition of a fly back hand (rattrapante) significantly increases the potential uses for chronographs. It makes possible the measurement of split-second times or timing simultaneous events of unequal duration.

The register is another name for a sub dial that is usually found within the watch?s main dial. An example is a chronograph where there are registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.

A repeater is a device that chimes the time when the wearer pushes a button. Some repeaters, called "quarter repeaters" sound the hours and the quarter hours by means of two different pitched tones. Others called "five minute repeaters" sound the hours, quarters, and five minute periods while "minute repeaters" sound the hours, quarters, and minutes.

Retrograde is used to describe a pointer-hand on a watch dial (often called a sub dial), which returns to zero at the end of a set period. For example, a watch may have retrograde date where the hand moves up a scale, pointing to the current date - when it reaches 31 it will spring back to 1.

Rhodium plated is the protective coating of metal with a thin layer of rhodium. It is a hard, brittle metal that does not oxidize and is malleable only when red hot.

A rotating bezel (the ring surrounding the watch dial) that can be turned in order to perform different timekeeping and mathematical functions.

A rotor is the part of an automatic (or self-winding) mechanical watch that uses movement to wind the mainspring. It is a flat piece of metal, usually shaped like a semicircle, which swivels on a pivot with the motion of the wearer's arm.

Synthetically formed, the sapphire crystal of a watch is extremely scratch resistant (nine on the Moh scale) and is the material of choice for many watch collectors. The downsides are that the sapphire can chip at the edges if it protrudes and it can shatter.

Sapphlex crystal (found on Seiko watches) is a highly scratch-resistant crystal created by the fusion of sapphire and mineral glass crystal.

Commonly found on dive watches, a screw-down crown aids water-resistance by sealing the crown to the case of the watch. A seal is achieved when the case locks with the crown's internal threads and gaskets fastening the crown into its place. In order to adjust the date and/or time on a watch with a screw-down crown, you must first unscrew the crown before you can gently pull it out to its first or second click stop position. To do this, simply rotate the crown counterclockwise until it springs open. When you have finished setting the watch, the crown must then be pushed in and screwed back in tightly. Not doing so will cancel the water-resistance of the watch. Overall, this process should not require a lot of effort or force.

The second time zone indicator is an additional dial that can be set to another time zone. It lets the wearer keep track of local time and the time in another country simultaneously.

Self-winding refers to a mechanically powered watch that is wound by the motion of the wearer's arm rather than by turning the winding stem (manual mechanical). In response to this motion, a rotor turns and winds the watch's mainspring. Most automatic watches have up to 36 hours of power reserve. If an automatic watch is not worn for a day or two, it will need to be wound by hand to get started again.

As defined by U.S. government regulation, shock resistance is a watch's ability to withstand an impact equal to that of being dropped onto a wooden floor from a height of three feet.

A slide rule bezel is a rotating bezel or ring around the outside edge of the watchcase that displays a logarithmic or other scale. It is used to perform general mathematical calculations or navigational computations.

Light charges the battery. Tough Solar is found in the Casio G-Shock line.

Solar powered refers to a type of Quartz movement where the batteries are recharged via solar panels on the watch dial. They have a power reserve so they can run in the dark.

Solar tech is a solar powered Quartz watch. This technology provides the accuracy of Quartz, without the inconvenience and cost of regular battery changes.

A split second is a feature on a chronograph that is two hands: one is a fly back and the other is a regular hand. In order to time laps or different finishing times, the wearer can stop the fly back hand independently while the regular hand keeps moving.

Stainless steel is an extremely durable metal alloy (chromium is a main ingredient) that is virtually immune to rust, discoloration, and corrosion. It can be highly polished, thus resembling a precious metal. Stainless steel is often used on the backs of watchcases that are made of other metals. A metal of choice, stainless steel is used to make high quality watchcases and bracelets. It is also hypoallergenic because it doesn't contain nickel.

Sterling silver, a precious metal, refers to silver that is 92.5 percent pure. The silver fineness should be stamped on the metal, sometimes accompanied by the initials of a designer or the country of origin as a hallmark. A protective coating may be added to prevent tarnishing.

A stopwatch with a second hand measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a "chronograph."

A sub dial is a small dial used for several purposes, such as keeping track of elapsed minutes or hours on a chronograph, or to indicate the date.

The Swiss A.O.S.C. is a mark identifying a watch that is assembled in Switzerland with components of Swiss origin. It is primarily used in Bedat watches.

A label used to indicate that a wrist watch is made in Switzerland. A watch is considered completely Swiss-made if it contains a movement that is Swiss, if the movement itself is encased in Switzerland, and if any final quality control by the manufacturer occurs in Switzerland. This is current Swiss law, and changes may occur in the future.

The movement of a watch with Swiss movement has been assembled in Switzerland, the Quality Control check is completed in Switzerland, and the components of Swiss parts make up at least 50 percent of the total value, minus the cost of assembling the movement.

A tachometer is an instrument for measuring speed or units. In watch making, a timer or chronograph with a graduated dial shows speed in kilometers per hour or some other unit (see timer).

A tank watch is a rectangular watch with heavier bars on either side of the dial. It was inspired by the tank tracks of World War I and was first created by Louis Cartier.

Tantalum is a metal with a texture similar to titanium, but a color similar to gold. This metal is used by Omega for the gold-like trim on certain titanium watches. Many of these watches are also available in titanium with real gold trim.

A telemeter is a watch function that finds the distance of an object from the wearer by measuring how long it takes sound to travel that distance. Like a tachometer, a telemeter consists of a stopwatch function and a special indication on the dial of a chronograph.

Indicates temperature.

This shows high and low tides for your area. Calculated using the current time, GMT setting, Latitude and Longitude, and the Lunar Tidal Interval.

A timer is an instrument used for registering intervals of time without displaying the time of day.

Titanium is a "space age" metal, often having a silver-gray appearance. Because it is 30 percent stronger and nearly 50 percent lighter than steel, it has been increasingly used in watch making, especially sport watch styles. Its resistance to salt water corrosion makes it particularly useful in divers? watches. Since it can be scratched easily, some manufacturers use a patented, scratch-resistant coating. Titanium is also hypoallergenic.

A tonneau watch has a barrel-shaped watch case and two convex sides.

A totalizer is a mechanism that keeps track of elapsed time and displays it usually on the watch?s sub dial. It is sometimes called a "recorder" or "register." The term "totalizer" can be used more generally to refer to any counter on a watch.

The unidirectional rotating bezel, or an elapsed time rotating bezel, moves only in a counterclockwise direction and is often found on divers? watches. It is designed to prevent divers from overestimating their remaining air supply. Because the bezel only moves in one direction, the diver can err only on the side of safety when timing the dive. Many such bezels are ratcheted, so that they lock into place for greater safety.

A device used to allow the continuous running of automatic (self-winding) wrist watches when not in use. In general, automatic watches employ the use of a rotor, or a moving weight to wind itself when worn on the wrist. If the watch is not worn, there is no way to receive any additional power and the watch will eventually run out of its power reserve. While most automatic watches can be manually wound, a watch winder makes this process much easier, more convenient, and overall, safer for wrist watches, as there is no need to manually handle the watch.

Water-resistance describes the level of protection a watch has from water damage. A watch bearing the inscription "water-resistant" on its caseback can handle light moisture, such as a rainstorm or sink splashes, but should not be worn swimming or diving. If the watch can be submerged in water, it must state at what depth it maintains water-resistance, i.e. 50 meters (165 feet) or more on most sport watches. Below 200 meters, the watch may be used for skin diving and even scuba diving depending upon the indicated depths.

Waterproof: An illegal and misused term: No watch is fully 100% waterproof. Waterproof means the ability to completely exclude the possibility of water entering into any working portion of a watch. According to the Federal Trade Commission, no watch is fully 100 percent waterproof and no manufacturer that sells watches in the U.S. may label any of their watches as "waterproof." The FTC stipulates that watches be referred to as "water resistant."

The winding stem button resides on the right side of the watchcase and is used to wind the mainspring; it is also called a "crown."

Winding refers to the tightening of the watch?s mainspring. This can be done by hand (by the crown) or automatically (by a rotor, which swings due to movements from the wearer's arm).

Displays the current time in major cities and areas around the world.

A world time dial, usually found on the outer edge of the watch face, tells the time in up to 24 time zones around the world. The time zones are represented by the names of cities printed on the bezel or dial. The hour hand points to a city along a set scale enabling the wearer to determine the time zone.. Watches with this feature are called "world timers."

A timer that sounds warning signals during the countdown.

It is an addition to the mechanics of a watch escapement. Developed around 1795 by the French-Swiss watchmaker Abraham-Louis Breguet from an earlier idea by the English chronometer maker John Arnold, a tourbillon aims to counter the effects of gravity by mounting the escapement and balance wheel in a rotating cage, to negate the effect of gravity when the timepiece is stuck in a certain position.

Movement of a pendulum or other oscillating element, limited by two consecutive extreme positions. The balance of a mechanical watch generally makes five or six vibrations per second, but that of a high-frequency watch may make seven, eight or even ten vibrations per second.