Watch Glossary

ANNUAL CALENDAR – The Annual Calendar complication comprises a full or partial simple calendar that is capable of automatically accounting for months with 30 days as opposed to 31. As such, it only needs to be adjusted once a year on the 1st of March.

See also: complication.

ANTI-MAGNETIC – When a mechanical watch is described as anti-magnetic, this means the movement is protected from the impact of magnetic fields. This is important, as magnetism can have a detrimental effect on a mechanical movement’s ability to keep accurate time.

AUTOMATIC (SELF-WINDING) MOVEMENT – An automatic, or self-winding, watch features a watch movement equipped with a mechanism that generates power by using the movement of the arm to cause a rotor to rotate and which, via specific gears, winds the mainspring. Some automatic movements offer the option of manually winding as well, especially those with longer power-reserves.

See also: manual movement; oscillating weight (rotor).

ATM (ATMOSPHERE) – ATM is a unit of measure that indicates a watch's water-resistance, specifically its capacity to resist pressure. This measurement is based on standard atmospheric pressure defined as 101.325 kilopascals (kPa), which is equivalent to approximately 1 bar. To make things even more confusing, it is often expressed in different ways. For example; 10 atm = 10 bars = 100 metres.

BALANCE – Often visible on the back side of the watch movement, and sometimes even displayed on the dial side, the balance is a circular, moving part which oscillates on its rotational axis. It is coupled to the balance-spring which gives it the to-and-fro motion through which it divides time into strictly equal parts. Each to-and-fro movement ("ticktock") is called an oscillation, and each oscillation comprises two vibrations. Combined with the spiral it forms the regulating organ of the watch.

See also: frequency.

BALANCE COCK – Sometimes lavishly decorated, the Balance Cock is a movement bridge with a lug anchored to a stud. An index (or regulator) passes over a scale indicating whether the movement is running fast or slow. See also: index BALANCE SPRING – Look closely at the oscillating balance and you will spot this very fine spring in the middle, which is the "heart" of a mechanical watch. Its ends are affixed to the balance and the balance-cock. Its elasticity allows the balance to make regular oscillations. Its length, and the balance's moment of inertia, determine the duration of each oscillation and can be altered to regulate the watch.

BEZEL – The bezel of a watch serves both a functional and decorative purpose. First and foremost, its role is to secure the crystal protecting the dial to the case middle. However, the bezel also contributes significantly to the visual appeal of the watch, and often features a different finish from the rest of the case to help it stand out. Bezels can be thick or thin, and can provide additional indications, such as the hour track for a second time-zone.

See also: case; case middle; unidirectional bezel; tachymeter scale.

BLUED STEEL – Often used for watch hands, blued steel is steel that has been heated until its surface oxidises to become a nice bluish colour. This technique is also frequently used on the screw heads on watch movements to add further decoration.

BRIDGE – In watchmaking, a bridge is a metal plate under which the pivots of the wheels and pinions turn. Both ends of the bridge are secured to the plate by screws. Generally, a bridge is named according to its function, e.g. centre-wheel bridge, barrel bridge, balance cock, etc.

CABOCHON – A cabochon is a polished precious or fine stone cut into a dome and without facets. Cartier is famous for putting blue cabochons in the crown of its watches, and they can also be used to decorate the watch dial.

CASE – The case is the container that protects the watch movement from dust, damp and knocks. It’s also an important part of a watch’s visual appeal, and so its design is often influenced by fashions and buyers' personal tastes. Cases can be made from a variety of materials, including but not limited to: gold, platinum, steel, titanium and ceramic. The most common case shapes are; Round, Square and Tonneau.

CASE MIDDLE – The case middle refers to the central part of the watch case that houses the movement. The back and bezel are fixed to the case middle and it is sometimes made from a different material to ensure strength and rigidity.

CHRONOGRAPH – A chronograph is a watch, that in addition to indicating the time, also features a mechanism whose hand can be started, stopped and returned to zero on demand to measure a duration of elapsed time, accurate to one fifth, tenth or even hundredth of a second. Sub-counters for the minutes and hours (usually 30 minutes and 12 hours) keep track of how many times the Chronograph hand completes a full revolution of the dial. An exceedingly popular complication, it is also one of the most complex to develop and assemble due to the significant number of parts required.

CHRONOMETER – In the world of high-end watchmaking, a chronometer refers to a high precision watch with a small seconds display whose movement has been controlled over a period of several days, in different positions and at different temperatures, by an official neutral body. Only mechanisms that have satisfied the criteria for precision of ISO 3159, or its equivalent, are issued with an official chronometer certificate. In Switzerland, this certification is undertaken by the COSC.

See also: COSC.

CLOUS DE PARIS – Commonly referred to as “hobnail” in English, Clous De Paris is a guilloche pattern on the dial of hollowed lines that intersect to form tiny pyramidal shapes. This is a form of decoration and sometimes also appears on the bezel of a watch, for example the iconic Patek Philippe Calatrava Ref.5119-001.

See also: guilloche.

COMPLICATION – This refers to any function a watch performs, other than the indication of hours, minutes and seconds, regardless of whether the mechanism is hand-wound or selfwinding, mechanical or electronic. Examples include: power reserve indicators, annual calendars, moon phase displays, chronographs and minute repeaters.

CORRECTOR – Many watches fitted with indicators such as the date, moonphase, and the like, also feature a corrector button that is flush with the case middle. This little button is used for adjusting (correcting) the different indications as and when needed by means of a special tool.

COSC – The COSC (Contrôle Officiel Suisse Des Chronomètres) is a non-profit organisation based in Switzerland. It is responsible for awarding the title of "chronometer" to each watch whose accuracy and consistency of rate has been demonstrated over fifteen days of tests at one of its official testing facilities. The uncased movement is tested in five positions and at three different temperatures. Only movements which meet the precision criteria established under ISO 3159 are granted an official chronometer certificate.

CÔTES DE GENÈVE – This is a particularly popular type of decoration that features undulating lines, like waves, and is frequently used to embellish superior quality movements.

COUNTDOWN TIMER – As the name suggests, a countdown timer is a device for counting backwards over a given interval. This complication is typically used for timing Regattas so that the sailors know when to start.

CROWN - The crown is a button of various shapes, typically found on the right-hand side of the watch case (although it can be placed just about anywhere around the case.) Held between the thumb and forefinger it used to wind the watch, as well as set the time and date. It may also be used to set other functions on the watch, depending on the individual model. Some crowns also incorporate a push-button for operating a Chronograph mechanism or to release the cover of a hunter case.

See also: chronograph; hunter case.

DUAL TIME ZONE – As the name suggests, a dual time-zone watch is capable of displaying two time-zones simultaneously. Usually these are the wearer’s local time and the home time.

ESCAPEMENT - This mechanism is fitted between the gears and the regulating organ. Its function is to suspend the gears' motion at regular intervals and to supply energy to the balance. Although a few different versions exist, the Swiss lever escapement is the most widely used today because it is especially suited to watches and chronometers.

FOLDING BUCKLE – Also referred to as a deployant buckle, the folding buckle is an articulated buckle that unfolds when opened. This design ensures the watch stays fixed to the wrist more securely and it is often found on sports and tool watches. Should the buckle accidentally come open, it will still hold the strap sufficiently in place to prevent the watch from slipping off the wrist.

FLY-BACK – The fly-back function enables the chronograph hand to be instantly reset to zero and immediately started again by pressing once on the chronograph push-piece. This function is of particular use to pilots, as the process of stopping the chronograph, resetting it back to zero and then starting it again is simply too time consuming at high speeds.

See also; chronograph; split-second chronograph

FREQUENCY - The balance in a mechanical watch movement makes a to-and-fro movement at a given frequency (two vibrations). The number of oscillations it makes per second are measured in Hertz. The higher the frequency, the more accurate the watch: 21,600 vibrations/hour (3 Hz), 28,800 vibrations/hour (4 Hz) and 36,000 vibrations/hour (5 Hz).

See also: balance; hertz.

GRANDE SONNERIE – A Grand Sonnerie is a special type of watch that strikes the hours and quarters in passing and repeats the hour at each quarter. A slide or push button on the side of the watch case allows the hour and quarter strikes to be repeated on demand.

See also: repeater.

GUILLOCHÉ (ENGINE-TURNING) – Often appearing on the movements and dials of high-end mechanical watches, Guilloché is a style of hand or machine engraving with intersecting wavy or straight lines. When the piece is moved horizontally or vertically against the tool, the finished effect is guilloche. When the piece is moved radially against the tool, the finished result is flinqué or flinking.

HERTZ - A unit of frequency of a periodic phenomenon equal to one cycle per second.

HUNTER CASE – This refers to a watch whose case has both a front and back cover, normally attached to small hinges. The covers protect the dial and the caseback from dust as well as potential damage and can sometimes be elaborately decorated or engraved with a coat of arms or something similar. A watch case with only one cover – usually on the back – is called a Half-Hunter.

INCABLOC® - The Incabloc® system features a resilient bearing that is designed absorb shocks to the balance-staff pivots without itself being damaged. Also known as shock-proofing, the majority of watches today use this system. 

See also: balance.

INDEX – The index, or regulator as it is often called, is used to adjust the rate of a watch by increasing or reducing the effective length of the balance spring. The index is a steel lever, the shorter end of which carries the curb pins which embrace the spring, and the longer end of which passes over a scale marked F and S (fast and slow). The index is friction-fitted on the balance's end piece. The watch is regulated by moving the index forwards; the result of this can be gauged from the graduations on the balance cock.

See also: balance cock; balance spring

JEWELS - Jewels (rubies), are used in watch movements as bearings for pivots to reduce friction. Typically, a high quality mechanical watch movement will have been between 15 and 21 jewels, although it can be much more than this.

JUMPING HOUR – The jumping hour is an unusual complication whereby the hour is shown digitally through an aperture, and it instantly changes (jumps) every 60 minutes to the next hour.

LARGE DATE – Unlike a standard date display, which displays the date on a single rotating disc, a large date display features two large numerals on two independent discs, displayed through oversized apertures.

LUGS – Also referred to as case horns, the lugs are the part of the watch case where the bracelet or strap attaches. The size and shape of the lugs can play an important role in how comfortably a watch fits on the wrist, as well as playing an important part in the overall aesthetic of the watch.

LUG WIDTH – This measurement refers to the distance between the lugs of the watch and determines the width of the watch strap or bracelet that will fit the case. It’s important to check this measurement before ordering a replacement strap or bracelet for your watch.

LUMINOVA® - LumiNova® and Super-LumiNova® (or lume) are a luminous substance, generally used to coat the hands and numerals on a watch dial (it may also be applied bezels as well). It stores light, which it then emits in the dark causing the hands and numerals to glow and continue to be visible, enabling the wearer to still read the watch indications in low-light conditions.

MANUAL MOVEMENT – Unlike an automatic (self-winding) movement, a manual movement requires the mainspring to be wound by hand using the winding crown to generate power. This power is then stored and released over a defined period. See also: automatic (self-winding) movement; crown; power reserve indicator.

MANUFACTURE – The term ‘Manufacture’ is often used in the Swiss watch industry to differentiate between a company that manufactures a watch almost in its entirety as opposed to those which buy in the parts from third-party suppliers and assemble and time the watch, and fit the hands and movement, etc.

MOON PHASES – The moon phases mechanism and display represents the different phases of the moon. A complete lunar rotation takes 29 days, 12 hours, 44 minutes and 2.8 seconds and is divided into four phases; the new moon, first quarter, full moon, last quarter.

OSCILLATING WEIGHT (ROTOR) – Also referred to as the rotor, the oscillating weight is a heavy metal, half-moon disc that turns freely in both directions to wind the mainspring. It is only found in automatic (self-winding) movements and is often embellished or decorated in some way.

See also; automatic (self-winding) movement.

PEPERTUAL CALENDAR – Like the Annual Calendar complication, a Perpetual Calendar is capable of automatically accounting for months with 30 days as opposed to 31. However, unlike the Annual Calendar, it also capable of calculating and adjusting for the 28 days in February, as well as leap years. Some models only require adjustment once a century, whilst others can account for hundreds of years without adjustment – assuming the watch is continually kept running.

POWER RESERVE INDICATOR – Typically only found on manual watches, the power reserve indicator provides a visual representation of how long the watch will continue to function before the mainspring must be wound again. The indicator is typically shown on the dial side of the watch, however, it may sometimes be placed on the movement side.

See also: manual movement.

REPEATER – Considered the ultimate complication, a repeater is a watch that strikes the hour on demand when the wearer activates a special push-piece or a slide on the watch case. There are several different types of repeater, including a half-quarter and quarter repeater, a five-minute repeater, and of course, the ever-popular, minute repeater.

RETROGRADE - An hour, minute, seconds or calendar hand which moves across a set scale and, at the end of its cycle, returns immediately to zero to begin again.

SKELETON MOVEMENT – A skeletonized movement is without doubt truly a sight to behold. The plate and bridges are cut away partially or fully to expose the wheels, leaving only the bare essentials the watch needs to function. The movement is then placed between two sapphire crystals so that the handiwork can be appreciated in all its glory.

SPLIT-SECONDS (CHRONOGRAPH) - The split-seconds chronograph is used to time different events that begin at the same time but do not end together. When first activated, the hands of the chronograph move in-sync with one another. When the first event ends, the pusher is pressed again, which stops the split-seconds hand, whilst the chronograph hand continues uninterrupted. After reading the intermediate time a second push on the same button causes the split-second hand to instantly ‘catch-up’ with the chronograph hand and the two continue their movement around the dial together. At the end of the second event, the split-seconds hand is stopped again to read this second intermediate time, and so on. At the end of the last observed event, both hands can be stopped and returned to zero. One pusher operates the split-seconds hand only, while the second pusher operates both hands.

See also: chronograph; fly-back.

TACHYMETER SCALE – Often found engraved on the bezel of racing inspired sports watches equipped with a chronograph mechanism, a tachymeter scale can be used to compute a speed based on travel time or measure distance based on speed. The individual spacing between the marks on the tachymeter dial are proportional to 1/t, where ‘t’ is the elapsed time.

See also: bezel; chronograph.

UNIDIRECTIONAL BEZEL - The bezel on a diving watch is unidirectional. This is a deliberate feature and an additional safety factor as the bezel only rotates in the direction that will reduce dive time. Hence if the bezel is accidentally turned, the diver can still surface with sufficient air and observe decompression stops.

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