Watch words: The terminology of timepieces explained
We cover a lot of stories about wristwatches and other techy timepieces on New Atlas, but horology can be a difficult subject to approach, filled as it is with all sorts of strange terms – like horology. To peel away some of the mystery, we've put together a glossary of watch terms to help neophytes and not-so-neophytes get up to speed.
Also called a 12-hour register. A stopwatch or chronograph subdial to track 12-hour intervals.
Also called Military time. Time measured in 24-hour intervals instead of 12-hour intervals with am and pm. So called from its use by the military to avoid ambiguity.
Also called a 30-minute register. A stopwatch or chronograph subdial to track 30-minute intervals.
A plastic used to make crystals. It's very soft, but is easy to repair and does not shatter when it breaks. Watches designed for use in space have acrylic crystals.
A display of time or other data using dials and hands, as opposed to a digital readout. After a hiatus in the 1980s, the format has become increasingly popular.
A watch display that combines analogue and digital elements, usually found on Quartz watches, though there are some mechanical versions
A type of mechanical watch movement that is designed to be highly resistant to magnetic fields that could adversely affect or stop it.
A box or cabinet with motorized rotating slots to hold watches with automatic movements. The rotation keeps the watch wound by spinning the movement's rotor, and accurate by counteracting the effects of gravity. Some winders are incorporated into special safes to hold collector automatic watches that cost six figures.
Also called self-winding or simply automatic. A mechanical watch movement that is wound by the motions of the wearer by either spinning a rotor or oscillating a weight. Failure to wear the watch regularly will cause it to stop once its power reserve is exhausted, which is annoying.
The oscillator on a mechanical watch that regulates the movement so it runs in a series of beats or vibrations.
An oscillating wheel that regulates the movement by dividing time into regular beats
A bridge with a lug anchored to a stud. It holds the top pivot of the watch's balance staff.
A ring around the watch face made of stainless steel, ceramic, precious metal or base metal. It can be either decorative or movable. If the latter, it may be inside or outside the crystal and rotate to act as a timer, tachymeter, slide rule, or other function.
Bi-directional rotating bezel
A bezel that can rotate either clockwise or anticlockwise to perform a function.
A watch band made of movable links. These can be adjusted to fit the wearer and may have special clasps that allow them to expand to fit over a wetsuit or jacket.
A plate or bar set on a movement's main plate to act as a frame to hold a watch's inner workings. They can also be shaped or decorated in skeleton watches for aesthetic purposes.
A complication that shows the date and may also show the day of the week, the month, or even the year. Some calendar watches need to be adjusted manually whenever the month is less than 31 days long. Others, called perpetual calendars, are self-adjusting over several decades or centuries.
An arched or curved bezel or dial.
The housing used to protect the movement. Usually made of base or precious metal, it can also be made of plastic, carbon composite, ceramic, rubber, or other materials.
The back or reverse of a watch designed to protect the movement. These are generally made of stainless steel, though they may include a crystal to show off the workings inside. Case backs may be simply snapped in place or screwed in with rubber gaskets to protect against water and dust. These often include information about the watch, like hallmarks, major specifications, or a serial number.
A ring of symbols or marks on a watch dial to indicate minutes or seconds.
Large marks on a chapter ring to denote hours. Quarter hours often have their own chapters.
A complication that allows a watch to act as a stopwatch with a precision of down to a tenth or a hundredth of a second. Some versions allow lap timing as well for individual contestants in a race or events in a process.
A precision timepiece capable of keeping time with a precision and accuracy suitable for navigation. Swiss-made watches are certified as chronometers by meeting the standards set by the Swiss Official Chronometer Control (COSC), which includes several days of rigorous testing under various pressures and temperatures. The depressing thing is that a one-dollar quartz watch can often outperform a US$8,000 luxury timepiece.
Fastening mechanism for straps and bracelets. Leather, rubber, and cloth bands tend to use buckles, though bracelets and expensive leather straps use deployment straps for a tighter fit with less wear.
Any function on a watch beyond displaying hours, minutes, and seconds. These can include even unseen things like an automatic winding function or a tourboulin. Some complications, like thermometers and altimeters, don't involve time, so their inclusion tends to start arguments in horological circles.
A chronometer developed and named by Rolex that has a tachymeter mounted on the bezel instead of the dial.
A complication that counts down in reverse from a preset time, like for timing an egg or a parking meter. This can include an alarm to alert the wearer when the time has elapsed, though that is usually found on quartz watches.
An illegal copy of a watch that is passed off by the maker as the real thing.
A button on the side of the case that pulls or screws out, allowing the wearer to adjust the time and date or synchronize the seconds. In non-automatic watches, it is also used to wind the mainspring. Screw-in or screw-down crowns, or similar mechanisms, seal the watch to keep out water at extreme depths.
A transparent cover over the dial or in the case back, or it may make up the entire case. It can be made of ordinary glass, mineral glass, acrylic plastic, synthetic sapphire, or ruby. Sapphire is preferred for high-end watches because it's almost as hard as diamond, though many use plastic because it's easy to repair and cracks instead of shattering into small, potentially dangerous fragments.
A small blister on a crystal that acts a magnifying lens to make the date more legible. This is appreciated by those of us of a certain age who are certain that watchmakers are making the date windows tinier and are even sneaking into our homes and doing the same to watches we already own.
A watch with indicators or windows to display both the date and the day of the week. These require a more complicated mechanism to allow them to be adjusted quickly without jamming.
A colored indicator on a dual or world time watch that shows if the home and second time zones are in daylight or night. It's particularly useful for watches without a 24-hour readout.
A buckle that allows a strap or bracelet to stay in one piece, by opening and fastening using a hinged plate with adjustable extenders. The latter are particularly popular with divers or aviators, who may need to adjust the band to go over a wetsuit or jacket.
The face of the watch, which carries the hands, marks, indicators, and subdials. A dial may be plain, highly ornate, or divided into bridges to make the movement visible.
A watch that shows the time and other information through a digital display instead of with hands. Digital watches are associated with quartz watches first marketed in the 1970s, which used LED and LCD displays, but mechanical digital watches date back to the 19th century and have appeared from time to time as novelty items. It was widely believed in the 1970s and 80s that digital watches would not only drive out analog ones, but analog timekeeping as well. However, recent decades have seen a resurgence of analog watches with digitals withdrawing to the cheapest or most specialized markets.
Also called a diver or diver's watch. A watch with a case designed to remain water resistant to depths of at least 200 m (660 ft). It also includes a dial designed to be legible at a glance under poor light conditions, and may have an elapsed time bezel for timing decompression stops. These have been superseded by wrist dive computers, but most divers still wear a dive watch as a back-up.
A watch that is robust, easy to keep clean and sterile, and has a special seconds hand and markings to allow a doctor to quickly measure a patient's pulse.
A water-resistant watch that is suitable for swimming, snorkelling, boating and other water sports.
A watch that is able to display the time in two separate time zones simultaneously.
A rotating bezel for tracking elapsed time by lining up the zero mark with the minute hand, so the result can be read directly.
Electric or electronic watch
A watch that runs on electric current instead of a mechanical movement. This generally refers to a quartz movement, but can also be used in regard to watches using tuning forks or other electric or electronic regulators.
End Of Life. This is an indicator on quartz watches that shows that the battery is almost exhausted and needs replacing.
Equation of time
A complication that shows the difference between true solar time and mean solar time. The Equation of time complication shows by how much the two times diverge from one another on a particular day.
The part of the watch movement that divides the time into a series of beats or oscillations. There are so many versions of the escapement that they could fill a museum.
A watch originally designed to be issued to soldiers for use on the battlefield. They are notable by their simple, rugged, and easy to service construction.
A hand on watches and especially chronographs that immediately jumps back to zero. On a regular watch, it can be used to conserve space on the dial by having a minute or second hand travel along an arc instead of revolving around the whole dial. When it reaches the end, it jumps back to zero in an instant.
On chronographs, the flyback hand is used to record elapsed time, and restarts the instant it is reset to zero without the need to stop and start the watch again. It's particularly useful when repeatedly timing a series of events.
A measurement of a watch movement's speed as measured in the number of semi-oscillations or half-turns of the balance spring. These are measured in beats or vibrations per hour (bph, vph) or Hertz. The higher the frequency, the smoother and more accurate the movement – which is especially useful in chronographs that measure in hundredths of a second. A modern wrist watch usually has a frequency of 4 Hz (28,800 vph).
A general term for the things that a watch can do. The term is different than a complication because functions can include basic timekeeping.
An obsolete way of equalizing the power of a mainspring as a watch unwinds by using a chain wound around a spiral-grooved, truncated cone. As the watch winds down, the chain is unwrapped from the narrow top of the cone and onto the mainspring barrel. Because the mainspring has less force as it unwinds, the chain sitting in progressively wider grooves of the spiral compensates and the watch runs properly.
A rubber ring set in a watch case back, crown, or crystal to protect against water and dust. Improper replacement while servicing can ruin your whole day.
The series of gears of a watch movement that runs between the mainspring and the display or a complication. The arrangement controls the running of the watch.
Also called the "Poinçon de Genève." The official seal of the City and Canton of Geneva, Switzerland. In horology, it's used as a quality seal by the Watchmaking School of Geneva on watches made in the Canton that have been submitted for and passed a special inspection. This is based on 12 criteria regarding the movement's materials and finishing.
Also called "Geneva stripes" or "côtes de Genève." These are decorations consisting of stripes applied to a watch's plates, bridges, balance cocks or rotors.
Greenwich Mean Time (GMT) is the time at the Prime or Zero Meridian that runs through the Royal Observatory at Greenwich, England and is not subject to summer time or daylight savings time. It's often confused with Coordinated Universal Time (UTC), but the latter is actually a precisely determined scientific time standard, which is constantly adjusted to remain in step with time as it is marked by an atomic clock.
A watch with a second hour hand that is set to mark the time at Greenwich. In conjunction with a special 24-hour bezel, it allows the wearer to quickly read the time in different zones. Alternatively, the additional hand can be set to any desired second time zone.
A way of giving a watch case or bracelet the look of gold by electroplating it with a layer of the precious metal. Since the thickness of such plating is only a few microns, the finish is subject to wear in daily use. For this reason, many watches are available in two-tone finishes to preserve the gold by restricting it to less vulnerable areas of the watch.
A highly valued watch – usually one that's out of the price range of the person who desires it.
A mechanical watch that includes a large number of functions or complications. Such watches are not meant for practical use, but as showcases for craftsmanship.
A watch or other timepiece that chimes at the hour, half hour, and quarter-hours automatically or when the wearer presses a button. The mechanism often includes different chimes of different pitches to allow the wearer to determine the time within the quarter-hour by hearing alone. Very elaborate versions may even include an automaton like a small singing bird.
Also called Engine Turning. This is a very precise engraving technique designed to produce intricate, repetitive designs on a material, including those used on dials.
Also called a balance spring. The very fine metallic spring in a watch movement that allows the balance wheel to recoil. Its length can be adjusted to regulate the watch by making it run faster or slower.
Also called hack seconds or stop seconds. A hacking seconds function allows the wearer to stop the seconds hand, usually by pulling out the crown to a preset stop, while the rest of the mechanism continues to run and keeps the time. It's used to synchronize the watch with someone else's or with a reference time signal without having to adjust the time.
A form of consumer protection going back 700 years. These are marks stamped on a watch case by a company or some official body that conveys information. They can guarantee the purity of a precious metal used in the case, the quality of the watch as determined by independent inspectors, the country or city of origin, water resistance, serial numbers, manufacturer, year of manufacture, caliber reference, or trademark.
Also called a manual-wind movement. A mechanical movement that requires periodic winding by hand to function. These often include mechanisms to prevent overwinding, but nothing to deal with the frustration of forgetting to wind the watch and finding yourself with a dead timepiece.
The part of the watch display used to convey information. The hands can come in many forms for aesthetic or practical reasons. In tool watches, it is common for the hands to be shaped as to be difficult to mistake for one another.
Upmarket watchmaking. The term is a play on the fashion industry's haute couture, and creations can sometimes be just as outré.
A metal casing made by cementing together titanium and tungsten carbide particles in a high-pressure press. The result is an extremely hard, scratch-resistant material that can be polished with diamond powder. However, it is also very brittle and cannot be repaired if damaged.
Helium escape valve
Also called a helium release valve. A valve set in a dive watch to prevent it from being damaged by helium. Dive watches with water resistance ratings of over 300 m (1,000 ft) are often worn by mixed-gas divers, who breathe a mixture of helium, hydrogen, and oxygen when working at extreme depths.
In between dives and when returning to the surface, the divers sit in a compression chamber filled with the same gas mixture. Because helium molecules are so tiny, they can slip past the watch's gasket and into the case. When the divers leave the chamber and return to sea level pressure, this trapped gas could severely damage the watch, so the one-way helium release valve is used to bleed off the helium when the internal case pressure becomes too great.
Unit for measuring frequencies in cycles per second. It's abbreviated as "Hz."
A kind of acrylic crystal.
A watch that deliberately mimics the design cues of a classic and far more expensive watch without pretending to be that watch, as opposed to a counterfeit or, worse, "replica." It allows someone to have a watch that has the look and feel or a Rolex or Cartier without going bankrupt or feeling dishonest. However, purists still frown on them as the chronogrpahic equivalent of a celluoid dickey.
The study of time measurement, sundials, clocks, chronometers, watches, and other timepieces, and their construction. Like chess, it is a field where a gnat may wade and an elephant can drown.
A watch that combines mechanical and smartwatch components.
A device that lights up the display on the watch on command. This can include simple electric lights; LEDs; photoluminescent materials like Super-LumiNova, LumiNova, or LumiBrite that absorb and re-emit light; phosphorescent materials embedded with radioactive isotopes like radium; and tritium-filled tubes called trasers among others.
A brand of shock absorber for mechanical watches designed to protect a movement's watch balance staff.
A simple mark on a watch dial designed to indicate the hours.
A watch strap or bracelet that blends into the case and is not detachable. It's most commonly found on fashion watches with a plastic or silicone rubber case and strap.
Sorry, this hasn't anything to do with jewels in the ornamental sense. These are sapphires or rubies (usually synthetic) that are shaped into gear bearings to reduce friction and increase the life of the movement between servicing.
Instead of using analog hands and marks on a dial, jump hours or minutes are a way of producing a digital display using a mechanical movement. In a jumping display, numbered discs rotate behind the watch face and are made visible through an aperture. It's called a jumping display because, where hands move gradually from one mark to the next, the numbers in the aperture remain static until the next minute or hour arrives, then jump ahead.
Also called deadbeat seconds, this is a way to make mechanical watch movements shift the seconds hand in discrete one-second intervals in a single tick like a quartz movement. Pendulum clocks have used deadbeat seconds since 1675, but modern mechanical movements usually tick five to ten times per second. Some haute chronologie watches can be made to display deadbeat, though the reason for doing this is simply to show off the complex mechanism needed to achieve it.
The standard for showing the purity of precious metals indicated by the abbreviation "k." 24k gold is pure, but 18k gold is 75 percent pure. The addition of other metals to gold is required because pure gold is too soft to be practical.
Loops on a watch strap or band designed to keep the surplus end length of the strap in place after its been fastened.
A technology developed by Seiko for its superquartz movements. Its purpose is to change the wearer's movements into electricity to keep the watch battery fully charged.
A chronograph or stopwatch function that can record the time for individual events in a race, including a runner's laps. When each lap is counted, it returns to zero to time the next lap.
Also called an anchor escapement. An escapement that uses an anchor-shaped lever with two pallets to lock and unlock the escapement wheel's teeth.
A watch that is manufactured and sold in a finite number of units that are often numbered. The purpose is to increase their value.
Liquid crystal display (LCD)
A flat display on a digital watch that uses liquid crystals sealed in a layer between two transparent plates in a series of sections. When an electric current is applied to a section, its optical properties change and it becomes opaque. This allows it to display digits, letters, and symbols depending on the display's design.
Curved protrusions from a wristwatch case for the attachment of a strap or bracelet by means of spring-loaded pins
Light emitting diode (LED)
A display that uses diodes that emit light when energized. These were used in the first digital watches but were so energy-hungry that they could only be illuminated for a fraction of a second by pressing a button, with the display being invisible the rest of the time.
A historic French unit of measurement used in watchmaking, equivalent to 2.2558291 mm.
The primary base plate that acts as the foundation for a watch movement.
The spring on a watch that provides it with power to operate. It's usually formed from a flat, spiral torsion spring of spring-steel ribbon set in a barrel attached to a toothed disk. As it uncoils, it rotates slowly on its arbor and keeps the gear train in motion.
A watch component that keeps the mainspring from overwinding and ruining one's day.
A watch that must be wound by hand at regular intervals. A manual watch can usually run from 36 to 48 hours.
A watch movement powered by a mainspring through a gear train and an escapement. It has no electrical power supply.
A rotor in an automatic watch that is small and thin enough that it can be set inside the movement instead of rising on top.
See 24-hour time.
See Field watch.
The most common type of material used in watch crystals. It's made of natural or synthetic glass that has been chemically or heat tempered to a hardness level of 5 to make it scratch-resistant.
A repeater watch that chimes the quarter hours and minutes after the hour, but not the hour itself.
Moon phase display
A complication that displays the age or phase of the moon as it waxes and wanes, often with two miniature moon discs rotating beneath the display, which become visible through an aperture.
Also called a caliber. The inner mechanism of a watch that allows it to operate, mark time, and perform its various functions. The three main movements are mechanical, automatic, and quartz. A watch company may make its own movements or buy them from a third party to put in its watches.
A stopwatch that can be started, stopped, and reset with a single button rather than two.
Also called the dial train. The gear train that connects the central wheel arbor to the hour hand and is engaged when the crown is pulled out to precisely set the hour and minute hands.
A nylon fabric strap with an extra keeper strap added to run behind the watch and prevent it from falling off if one of the lug springs should give way. It's designed to be easily set to a number of sizes, including over clothing. It was originally developed by the British Ministry of Defence in 1973 and gets its name from a shortening of the term "NATO Stocking Number."
A base metal that was once commonly used to make watch cases and was often plated with gold, silver, or chromium. However, because many people show an allergic reaction to nickel, it's being phased out. When nickel is used, it is encased in one or two layers of copper, then plated with gold or rhodium.
A watch that is robust, easy to keep clean and sterile, and has a pulsimeter to allow a nurse to quickly measure a patient's pulse. It differs from a doctor's watch in that it is built upside down so it can be pinned to a blouse and still be legible.
Flexible three-link metal bracelet with a deployment clasp. Named after the Rolex Oyster, which it is mostly associated with.
A calendar complication that can automatically take into account the number of days in the month, leap years, and other factors depending on its complexity.
A complication that chimes the hours.
An oversized watch with large, legible numerals and illuminated marks. It was originally designed for use by military pilots.
A precious metal often used in watch cases for its value and aesthetic properties. It also has hypoallergenic properties, so it's an expensive way of avoiding wrist rash.
Technically, quartz watches do not use batteries, they use power cells. A battery, as the name implies, is made of one or more power cells stacked together. Because watches are small and need little power, on a single power cell is needed.
A measure of how much energy is stored in a watch movement, as measured in hours of remaining running time.
Power reserve indicator
A readout on a watch showing how much mechanical or electrical energy remains for the movement.
A special scale on a doctor's or nurse's watch that directly reads out the patient's calculated pulse rate as measured by the seconds hand.
Also called buttons or push pieces. These are buttons on a watch that start, stop, and adjust its various functions.
Physical Vapor Deposition (PVD)
An alternative to electroplating to provide a watch or its parts with a gold finish. PVD involves placing stainless steel parts in a sealed high-pressure chamber, where they are exposed to evaporated gold. Instead of plating the steel, the gold molecules are infused deep into the base metal's crystalline structure, resulting in a more durable 22k gold finish that is resistant to ultraviolet light, moisture, wear, and discoloration.
A silicon oxide crystal, usually synthetic, with piezoelectric properties. It's formed into small plates and when an electric impulse is applied, the crystal vibrates 32,768 times a second, allowing it to act as an extremely accurate resonator that makes even a cheap quartz watch as accurate as the best mechanical marine chronometer.
A digital or analog watch movement that uses a quartz crystal to keep precise and accurate time. This is the most common watch movement used today.
A radioactive element once used to illuminate watches by mixing it with phosphorus and painting it on the dial or markers. It was phased out when it was discovered to be too radioactive to use on personal items.
A watch where the hours, minutes, and seconds are read off of three separate and distinct subdials.
A watch that announces the time in a series of chimes when a button is pressed. Repeaters can chime minutes, quarter hours, or hours, depending on their design.
Also called a split-second chronograph. A chronograph watch that uses two seconds hands. These run together when activated, but one can be stopped independently to record laps and other events.
A copycat of another manufacturer's watch down to the logo, but openly sold as a fake at a drastically discounted price.
A watch that uses an arc rather than a full circle of the dial to display the time. When the hands reach the end of the arc, they instantly jump back to the beginning and start over.
Also called pink or red gold. Its soft, reddish color is due to a mixture of copper with the gold.
A bezel that can be turned clockwise or anticlockwise. Rotating bezels can be used for something as simple as marking elapsed time, to as complex as turning the watch into a slide rule or some other specialized calculator.
An asymmetrical, axe-shaped weight designed to spin in reaction to a wearer's movements. This spinning action keeps an automatic mechanical watch movement wound. Collectors often use automatic winders to power up watches while in storage.
A crystal made of synthetic sapphire, which is transparent, but also slightly less hard than diamond, so it is scratch and shatter-resistant. It is also harder to work or repair than some alternatives, like plastic.
Mineral glass that has been toughened by a coating of sapphire to improve its scratch resistance.
Also called a screw-down or screw-lock crown. This is a special crown with screw threads and a gasket that allows it to be screwed into place, making the case watertight. To wind or adjust the watch, the crown must be unscrewed first. Because the threads are so small, special care must be taken when screwing it back in to prevent stripping.
Second time-zone indicator
A sub-dial on a watch that tracks the local time in another time zone in either hours or hours plus minutes.
See Automatic winding.
An official measurement of how well a watch can withstand impacts without suffering serious damage. The US standard is an impact equivalent to being dropped from three feet (1 m) onto a wooden floor.
A case designed to show off the internal mechanism of a watch. This can include using a crystal set in the back of the case, special skeletonized components, and even cases made entirely of sapphire.
Slide rule bezel
A bezel gradated to perform various mathematical calculations, including multiplication, division, speed over a fixed distance, fuel consumption, and others.
A computerized watch designed to act either independently or when paired via Bluetooth with a mobile device. The crystal of the watch acts like the touchscreen of a smartphone, and the watch can carry out a wide variety of functions.
A small cam that controls a movement's functions, especially in chiming watches.
A quartz watch that uses a photovoltaic cell set in its case or dial to keep the battery charged by converting ambient light into electricity. See Superquartz.
Split seconds hand
Also called spring bars or pins. Spring-loaded pins that run between the lugs on a watch case, that are used to attach a strap or bracelet.
A highly durable, corrosion resistant steel/chromium alloy. It's favored by many watchmakers not only for its hardness and toughness, but also for its ability to take a very bright shine that does not discolor or wear off. It's often used for cases, case backs, and bracelets.
A copper/silver alloy containing at least 92.5 percent silver. It's used in watch cases and bracelets, but it is prone to tarnish if not kept polished.
A specialized watch designed to record time in intervals down to a fraction of a second. It can also refer to a specific function on a chronograph watch.
Also subsidiary dial. A miniature dial set in the main dial of a watch to register information like hours, minutes, seconds, other time zones, day, date, or power reserve.
A quartz watch that includes self-charging technology, including solar cells of Kinetic drive. They suffer the drawbacks of obsolescence and difficulties in servicing.
An official designation for a watch that contains a movement made in Switzerland that contains at least 50 percent Swiss-made parts and is assembled in Switzerland.
A hallmark certifying that a watch is Swiss made.
Sweep seconds hand
A seconds hand that is mounted in the center of the dial. The smoothness of the seconds hand, whether it moves in a series of ticks, or in a single, smooth motion is an indication of how many vibrations per hour the movement generates.
Also called a tachometer. A complication found on some chronographs that calculates the speed of a vehicle after it travels a measured mile or kilometer. The seconds hand is activated as the vehicle starts the mile and stopped when it completes it. The readout on the dial is the speed.
A watch strap that resembles and works like a belt buckle.
A rectangular luxury watch designed by Cartier. The name comes from its resemblance to the treads on an army tank.
A function similar to a tachymeter, only it measures the distance sound travels rather than vehicle speed by tracking the difference between a distant event and the arrival of the sound associated with it.
A general term for a complication that registers intervals of time. If it goes forward, it's a stopwatch or chronograph, if backwards, it's a countdown timer.
A metallic element known for its strength and lightweight – both of which exceed that of stainless steel. It is hypogenic and has a pleasing grayish sheen. However, it is very difficult to work, so its application in watches is limited.
A watch case shaped like a barrel with a curving outline.
A watch made to carry out a practical task other than basic timekeeping to support a specific occupation, like scuba diver or pilot.
A dial that registers the complete elapsed time on a stopwatch or chronograph.
This has been described as the most popular, yet pointless complication on modern mechanical watches. It was originally created for pocket watches, which spent their time either sitting upright in a man's waistcoat or other pocket, or lying flat on a dresser at night. This introduced gravitational effects because it was generally in only one of two positions, so the tourbillon was introduced into the watch escapement to eliminate this effect by turning in every direction in a small, revolving cage. Wristwatches made the tourbillon obsolete because a watch on a wrist is constantly shifting position, canceling out gravity, but it's still included in modern watches because it's impressive to look at.
A gaseous radioactive isotope of hydrogen used to illuminate watches by sealing the gas in tubes painted with a phosphorescent material. These tubes can provide light for up to 25 years, but do not have the dangerous radiation of earlier radium watches.
A watch with two crowns with one for adjusting an winding the movement and the other to control some other function, like a rotating bezel mounted inside the crystal.
A watch or bracelet that combines two contrasting metals or metal platings, like gold and stainless steel.
Unidirectional rotating bezel
A bezel designed to only rotate anticlockwise, it's used on a diver's watch to track elapsed time in minutes. The advantage is that if the bezel is accidentally moved, it can only result in making an overestimate of the time underwater, which is not a dangerous mistake.
French acronym for Coordinated Universal Time. The 24-hour time at the Greenwich meridian. It's a precisely determined scientific time standard, which is constantly adjusted to remain in step with time as it is marked by an atomic clock.
An obsolete term for "water resistant." It was discontinued in the watch industry because it was ruled to be misleading and, therefore, illegal to claim.
An official designation for a watch case's ability to withstand water pressure as measured in depth as marked in meters, feet, or atmospheres.
An alloy of gold mixed with nickel or palladium to give it a silver or platinum-like color.
The act of tightening the mainspring of a watch using a crown, key or automatic rotor.
World time dial
A complication that tells the time in zones around the world. This can either be in the form of a dial marked with the names of cities in each of 24 time zones, or a hand that marks the time in Greenwich and a 24-hour rotating bezel for calculating the time in a particular place through addition or subtraction.
Also called a regatta timer, yachting chronograph, or sailing watch. A countdown timer configured for use in yacht racing, which involves reaching the starting line in a moving sailboat at speed just as the starting gun fires.
Gold that is either pure or mixed with zinc or copper to increase its strength while retaining its yellow color.
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