Watch terms glossary: 112 terms every buyer should know

A watch terms glossary explains the words dealers and listings use, so you can compare watches properly. This one has 112 terms, each defined in a sentence, in alphabetical order. Where a term has its own guide, the definition links to it. Definitions are general; a brand may use a word slightly differently.

For the full buying process, start with the guide to buying a luxury watch. This glossary is general information, not legal advice.

What do watch terms mean?

• Acrylic crystal: a plastic cover over the dial, sometimes called Plexiglas or Hesalite, cheaper and more shatter-resistant than sapphire but easily scratched.
• Aftermarket: a part not made by the original manufacturer and fitted after the watch left the factory, such as a strap, bezel insert or dial.
• Authorised dealer: a retailer formally appointed by a brand to sell its new watches; see Grey market below.
• Automatic: a mechanical watch wound by the movement of the wearer’s wrist through a rotor. See automatic vs quartz.
• Balance wheel: the oscillating wheel that regulates the timekeeping of a mechanical movement.
• Bezel: the ring around the dial, fixed or rotating, used for decoration or for timing.
• Bezel insert: the coloured ring, often ceramic or aluminium, set into a rotating bezel; a mismatched or chipped insert is a common flaw to check for on a pre-owned sports watch.
• Bidirectional / unidirectional bezel: a rotating bezel that turns both ways (used for GMT and compass functions) or only one way (used on divers’ watches, so a knock can only shorten, not extend, the elapsed time shown).
• Box only: a watch’s original box offered for sale without the watch, sometimes bought by owners trying to reassemble a full set.
• Bracelet: a metal strap made of linked sections; see how to resize a watch bracelet.
• Brushed finish: a matte, linear surface texture made by abrasion, used on cases and bracelets as an alternative to polishing; see Refinishing below.
• Buyer’s premium: a percentage fee added to the hammer price at auction; see watch auctions: a buyer’s guide.
• Cal. (calibre): the model name or number of a movement. Whether a brand makes its own calibres is covered in in-house vs outsourced movements.
• Caseback: the back of the watch case, solid or with a transparent window.
• Case back engraving: text or a design cut into the caseback, such as a presentation inscription; engraving usually lowers a watch’s value to collectors who prize an original, unmarked case.
• Certified pre-owned: a pre-owned watch inspected and sold with a guarantee by a brand or retailer; terms vary by programme.
• Chapter ring: a fixed ring between the dial and the bezel, often printed with a minute or tachymeter scale.
• Chronograph: a watch with a stopwatch function, usually operated by pushers on the case.
• Chronometer: a watch whose movement has been tested for accuracy by an official body such as COSC; see what COSC certification means.
• COSC: the Official Swiss Chronometer Testing Authority, a non-profit association founded in 1973 that certifies the precision of Swiss watches and movements as chronometers (COSC, checked 29 October 2026).
• Complication: any function beyond telling the time, such as a date, chronograph or moon phase.
• Condition grade: a seller’s label for a watch’s wear; see watch condition grades explained.
• Crown: the knob on the side of the case used to set the time and wind the watch.
• Crystal: the clear cover over the dial, usually sapphire, mineral glass or acrylic.
• Customs duty: a tax charged on some goods imported into the UK; see watch import duty and VAT.
• Cyclops lens: a small magnifying lens, usually set over the date window, that Rolex popularised; other brands use similar lenses under different names.
• Date window: the aperture in the dial that shows the date.
• Day-date complication: a complication showing both the day of the week and the date, usually spelled out in full on the dial rather than abbreviated.
• Deployant clasp: a folding bracelet clasp that opens and closes in sections.
• Dial: the face of the watch, carrying the hour markers and hands.
• Diameter: the width of the case, measured in millimetres, usually excluding the crown.
• Diver’s extension: a sliding or folding section on a bracelet or strap that lengthens it enough to fit over a wetsuit sleeve.
• End links: the bracelet links that connect directly to the case lugs; mismatched or generic end links are a sign of a non-original bracelet.
• Escapement: the part of a mechanical movement that releases power from the mainspring in small, regular steps.
• Exhibition caseback: a transparent caseback that lets you see the movement.
• Fauxtina: luminous material artificially coloured to look aged, imitating the cream or brown tint vintage lume develops over decades.
• Fluted bezel: a bezel with fine grooves cut around its edge, originally a way to grip it to open the case, now mostly decorative.
• Full set: a watch sold with its original box and papers; see what “full set” means.
• GMT: a complication showing a second time zone, usually with an extra hand that completes one rotation of the dial every 24 hours.
• Grey market: the sale of new watches through dealers outside the brand’s authorised network; see grey market versus authorised dealer.
• Guilloché: a fine, repeating engraved pattern cut into a dial, often by machine.
• Hacking seconds: a feature where the second hand stops when the crown is pulled out, so you can set the time precisely.
• Hammer price: the winning bid at auction before fees and tax are added.
• Hand-wound (manual): a mechanical watch wound by turning the crown.
• Helium escape valve: a one-way valve fitted to some divers’ watches that releases helium which has built up inside the case during long periods in a pressurised, helium-rich atmosphere, such as saturation diving; without it, gas expanding on decompression can force the crystal off.
• Hesalite: a brand name sometimes used generically for the acrylic crystal fitted to some watches, including models flown on space missions.
• Homage: a watch whose design closely follows a well-known model but which carries its own maker’s name; see what is a homage watch.
• Horology: the study and craft of measuring time, including watchmaking.
• In-house movement: a movement designed and made by the brand that sells the watch, rather than bought in from another maker; see in-house vs outsourced movements.
• Jewels: synthetic rubies used as bearings in a mechanical movement to reduce friction.
• Jubilee bracelet: a five-piece-link bracelet design introduced by Rolex, named to mark the brand’s 50th anniversary.
• Lacquer dial: a dial finished with a glossy or matte lacquer coating rather than being plated or enamelled.
• Lollipop seconds hand: a seconds hand with a circular disc near its tip, a style associated with some vintage dive watches.
• Lug: the projection on the case to which the strap or bracelet attaches.
• Lug width: the gap between the lugs where a strap or bracelet fits, measured in millimetres; see our watch sizing guide.
• Lug-to-lug: the measurement across the watch from the tip of one pair of lugs to the other, which affects how it sits on the wrist. Our watch sizing guide explains how to use it.
• Luminous: material on hands and markers that glows in the dark.
• Mainspring: the coiled spring that stores the energy driving a mechanical watch.
• Margin scheme: an optional UK VAT scheme for second-hand goods and some other items, under which VAT is charged on the difference between what the seller paid and what they sold the item for, rather than the full selling price (GOV.UK, checked 29 October 2026).
• Married (watch): a watch assembled, deliberately or not, from parts that did not originally leave the factory together, such as a case from one reference fitted with a dial from another.
• Mechanical: powered by a wound spring and regulated by a balance wheel; see mechanical versus quartz.
• Mother-of-pearl dial: a dial faced with the iridescent inner shell layer of a mollusc, giving a natural sheen that varies slightly between individual dials.
• Movement: the mechanism inside the watch that keeps time.
• NOS (new old stock): an unworn watch from past production that has never been sold.
• Oscillator: the part that provides a steady beat; a balance wheel in mechanical watches and a quartz crystal in quartz watches.
• Oyster bracelet: a three-piece-link bracelet design associated with Rolex’s Oyster case family.
• Papers: the documents supplied with a watch, such as the warranty card and manuals.
• Parallel import: goods imported and sold without the brand’s authorisation; see Grey market above.
• Patina: the natural ageing of a dial, hands or case, which some collectors value.
• Pie-pan dial: a dial with a stepped, sloped edge resembling an inverted pie dish, seen on some vintage models.
• Power reserve: how long a wound mechanical watch runs before it stops.
• Power reserve indicator: a dial display, usually a small subdial or arc, showing how much running time is left before a mechanical watch needs winding.
• Pre-owned: previously owned; the trade’s preferred word for second-hand.
• Provenance: the documented history of a watch and its owners.
• Pushers: buttons on the side of the case that operate a chronograph or other function.
• Quartz: powered by a battery and regulated by a vibrating quartz crystal.
• Quickset date: a mechanism that lets the date be advanced using the crown, without having to move the hands all the way around the dial.
• Reference number: the code a brand uses to identify a specific model and configuration.
• Refinishing (polishing): removing surface marks from a case, which also removes some metal.
• Rehaut: the inner flange of the case, between the dial and the crystal, sometimes engraved with a serial number or minute scale.
• Rotor: the weighted part inside an automatic watch that swings and winds the mainspring.
• Rotor noise: the sound, often a faint rattle or whirr, made by an automatic watch’s rotor as it swings; some is normal and model-specific, so compare against a known-good example of the same reference before assuming a fault.
• Sapphire caseback: a transparent caseback made of sapphire rather than mineral glass, used for most modern exhibition casebacks.
• Sapphire crystal: a scratch-resistant synthetic crystal used on many luxury watches.
• Screw-down crown: a crown that threads onto the case to improve water resistance.
• Screw-down pushers: chronograph pushers that thread into the case like a screw-down crown, used on some dive chronographs to improve water resistance.
• Serial number: the individual number engraved on a watch; see stolen watch check.
• Service: the cleaning, oiling, adjustment and replacement of worn parts in a movement; see how to care for a mechanical watch.
• Service history: the record of servicing and repairs a watch has had.
• Shock resistance: a watch’s ability to keep working after a knock, tested against a recognised standard such as ISO 1413 for wristwatches.
• Skeleton dial: a dial with parts cut away to show the movement.
• Strap: a flexible band, usually leather, rubber or fabric.
• Sunburst dial: a dial finished with fine radial brushing so it changes brightness as the light or the wrist angle changes.
• Swiss made: a label whose use on watches is set by a Swiss federal ordinance. Since 1 January 2017 a watch must have at least 60% Swiss value, a Swiss movement, and be cased up and finally inspected in Switzerland (Federation of the Swiss Watch Industry, checked 29 October 2026).
• Tang buckle: the traditional pin-and-strap buckle, similar to a belt buckle, as opposed to a folding deployant clasp.
• Tourbillon: a complication that mounts the escapement in a rotating cage.
• Trader: in consumer law, a person acting for purposes related to their trade or business; see consumer rights when buying a watch online in the UK.
• Tritium: a radioactive isotope once used in luminous paint; watches made before the mid-1990s may be marked “T SWISS T” or similar.
• Tropical dial: a dial, usually black, that has faded to brown or chocolate tones through UV exposure over decades; collectors use the term descriptively, not as a condition grade.
• Unworn: a watch that has never been worn by an owner.
• VAT: value added tax, charged at 20% on most goods in the UK (GOV.UK).
• Vintage: an informal term for older watches, with no agreed age threshold.
• Vintage reissue: a modern watch that reproduces the look of an older model from the same maker, usually with a current movement inside.
• Warranty card: a document recording the start date and terms of a manufacturer’s or dealer’s warranty; see watch warranty explained.
• Watch only: a watch sold without its original box or papers.
• Water resistance: a rating of how well a case resists water, shown in metres or bar and not a promise of depth performance.
• Winding: tensioning the mainspring, by hand or by the rotor.
• Wrist presence: the informal term for how a watch looks and sits on the wrist.
• Stolen-goods register: a database of reported lost or stolen property that buyers can check; see stolen watch check.
• Shipping insurance: cover for loss or damage in transit; see how watches are shipped and insured.
• Specified item: an item listed individually on an insurance policy; see watch insurance in the UK.
• Counterfeit: a copy made to pass as a branded watch; see how to spot a fake watch.

What do the abbreviations in listings mean?

Private-seller forums and auction sites favour short abbreviations over full words. This table covers the ones buyers ask about most; where a seller’s own abbreviation is unclear, ask rather than guess.

Source: general trade and forum usage; these are not standardised and sellers may use them differently.

Which buying terms matter most when comparing listings?

Four sets of terms change what you actually get. They are the ones to understand before you compare two listings.

Frequently asked questions

What is the difference between automatic and mechanical?

An automatic is a type of mechanical watch that winds itself from wrist movement. Hand-wound mechanical watches need winding with the crown.

What does “pre-owned” mean?

Previously owned. The trade uses it instead of “second-hand”.

What is a movement?

The mechanism inside the watch that keeps time.

What is a complication?

Any function other than telling the time, such as a date or chronograph.

What does “reference number” mean?

The code a brand uses to identify a model and configuration.

What does “serviced” mean?

The movement has been cleaned, lubricated and adjusted. Ask who did it and when.

What is the grey market?

Sales of new watches outside a brand’s authorised network. Read the guide linked above.

What is a trader?

A person acting for purposes relating to their trade, business or profession. UK consumer rights against traders are stronger than against private sellers.

This page is general information, not legal advice.

We check the facts in this guide against the sources named, and it is correct to the best of our knowledge as of October 2026. Rules, rates and sellers' terms change, so confirm the details with the seller, or with a professional, before you buy.