Watch glossary
What do the terms in a watch's specification list actually mean? We explain each one briefly and in plain language, alongside the models that have that feature.
86 terms
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A
- Annual calendarA calendar complication that automatically distinguishes between 30- and 31-day months.
- Anti-magneticDescribes watches designed not to be affected by magnetic fields from sources such as phones, speakers or magnetic bag clasps.
- Anti-reflective coatingAR coatingA thin coating applied to one or both sides of the sapphire glass to reduce reflections.
- Applied indexesApplied markersHour markers fitted one by one as separate metal pieces rather than printed on the dial.
- Automatic movementSelf-windingA mechanical movement that winds itself through the natural motion of your wrist.
B
C
- CalibreCaliberThe model name or number given to a watch's movement.
- CarbonCarbon fibreAn extremely light and durable material made by pressing carbon fibres with resin, layer by layer.
- Case diameterThe width of the watch case excluding the crown, measured in millimetres.
- CerachromRolex's name for its ceramic bezel inserts.
- CeramicIn watchmaking, a very hard, scratch-resistant material usually made from zirconium oxide.
- ChronographA function that measures elapsed time without interrupting the watch's normal timekeeping; in short, a stopwatch built into the watch.
- ChronometerA mechanical watch that has been tested to meet a specific accuracy standard.
- Co-Axial escapementCo-AxialAn escapement design that reduces the sliding friction between parts compared with a classic escapement.
- Column wheelA small, crown-shaped wheel that controls a chronograph's start, stop and reset functions.
- Complete calendarTriple calendarA calendar that shows the day, date and month together, often completed by a moon phase.
- ComplicationAny additional function beyond showing the hours, minutes and seconds.
- CrownThe knob on the side of the case used to set the watch and, on mechanical models, to wind it.
- Cyclops lensCyclopsA small magnifier set on the watch glass directly above the date window.
D
- DateDate windowThe most common complication, showing the day of the month.
- Day-dateWatches that show the day of the week and the date of the month together.
- Deployant claspFolding claspA clasp in which the bracelet or strap closes with folding metal blades.
- Diamond-setDiamond detailsThe use of diamonds on the hour markers, dial, bezel, case or bracelet.
- Dive watchDiver's watchA watch designed for use underwater, with high water resistance.
- DLC coatingDiamond-Like CarbonA thin carbon-based coating with diamond-like hardness.
E
- EnamelA dial technique in which powdered glass is applied to a metal plate and fired at high temperature.
- EscapementThe mechanism that divides the energy from the mainspring into small, equal portions and passes it to the gears.
- Everose goldEveroseThe name of the 18k pink gold alloy that Rolex makes in its own foundry.
- Exhibition casebackDisplay casebackA design in which a sapphire glass fitted into the back of the case lets you see the movement.
F
- Fluted bezelA bezel with fine vertical grooves cut into its surface, reflecting light in many directions.
- FlybackA type of chronograph that resets a running chronograph and restarts it immediately with a single press of a pusher.
- Frequencyvph / HzHow many times per hour a mechanical watch's balance wheel oscillates, usually written in 'vph' or hertz (Hz).
G
- Gem-set bezelA bezel set with diamonds or coloured precious stones.
- Geneva stripesCôtes de GenèveA decoration of parallel, wave-like stripes applied to the bridges of a movement.
- GMTSecond time zoneA function that lets the watch show a second time zone at the same time.
- GuillochéA technique of engraving fine, repeating patterns onto a dial or case surface using special machines.
H
- Hacking secondsStop-secondsA feature that stops the seconds hand when the crown is pulled out.
- HairspringBalance springA spiral spring as fine as a hair, attached to the balance wheel.
- Hand-woundManual windingA mechanical movement whose mainspring is wound by hand by turning the crown.
- Helium escape valveA small valve developed for professional saturation divers.
I
J
L
- Limited editionModels produced in a set number and often individually numbered.
- LugsThe projections extending from the top and bottom of the case, where the strap or bracelet attaches.
- Luminous coatingLume / Super-LumiNovaA substance applied to the hands and hour markers that stores energy from light and glows in the dark.
M
- Master ChronometerAn accuracy and durability standard that Omega applies together with METAS, the Swiss metrology institute.
- Micro-rotorA small rotor set into the movement at the same level, rather than covering it from above.
- Minute repeaterA complication that, when a slide or pusher is used, chimes the hours, quarters and minutes as small hammers strike gongs.
- Moon phaseMoonphaseA complication that shows how the Moon looks in the sky (new moon, crescent, full moon) in a small window on the dial.
- Mother-of-pearlA natural material taken from the inner surface of seashells that changes colour in the light.
N
O
P
- Perpetual calendarQuantième perpétuelA calendar that shows the correct date automatically, taking into account the different lengths of the months and leap years.
- Pin buckleTang buckleA classic buckle, similar to a belt buckle, that closes with a pin passing through a hole in the strap.
- PlatinumA white precious metal that is denser and heavier than gold.
- Power reserveHow long a fully wound mechanical watch will run without being wound again.
- PresidentRolex's bracelet made of semi-circular three-piece links and produced only in precious metals.
- PVD coatingPVDA method of applying a very thin layer to a metal surface in a vacuum.
Q
R
S
- Sapphire crystalA lab-grown watch glass that is one of the hardest materials after diamond.
- Screw-down crownA crown that is screwed tightly onto the case.
- SiliconA light, hard material used for parts such as the hairspring and escapement.
- SkeletonOpenworkedA design in which as much material as possible is cut away from the movement's plates and bridges.
- Slide ruleA device that uses two logarithmic scales, on the rotating bezel and around the edge of the dial, to multiply, divide and convert units.
- Small secondsSeconds shown on a small separate sub-dial instead of by a long hand at the centre of the dial.
- Split-secondsRattrapanteA chronograph with two chronograph seconds hands stacked on top of each other.
- Stainless steelThe metal most widely used for watch cases and bracelets.
- Sunburst dialSunrayA dial surface brushed in rays from the centre out to the edges.
- Superlative ChronometerRolex's name for its own accuracy standard.
T
- TachymeterA scale printed on the bezel or the edge of the dial, used to calculate speed.
- Tapisserie dialRoyal Oak TapisserieThe grid pattern of small raised squares that decorates Audemars Piguet Royal Oak dials.
- TitaniumA very strong metal that is about 40 percent lighter than steel.
- Tonneau caseTonneauA barrel-like rectangular case shape with sides curving outwards.
- TourbillonA mechanism in which the balance wheel and escapement are placed inside a rotating cage, usually turning once a minute.