Glossary of Watch Terms

Watch collecting has a precise vocabulary, and descriptions of vintage and pre-owned watches use it constantly. This glossary explains the terms you will meet, with notes on the words particular to Japanese watches.

Case and crystal

  • Case. The housing of the watch, in steel, gold, platinum, titanium or ceramic.
  • Bezel. The ring around the crystal, fixed or rotating.
  • Lugs. The projections that hold the strap or bracelet. Sharp lug edges suggest an unpolished case.
  • Crown. The winding and setting button. A screw down crown improves water resistance.
  • Crystal. The transparent cover, in acrylic, mineral glass or sapphire. Seiko calls its hardened mineral glass Hardlex.
  • Case back. The rear of the case, often engraved with the reference and serial numbers.

Dial and hands

  • Sunburst. A dial finish with fine lines radiating from the centre.
  • Guilloché. A pattern engraved into the dial by machine.
  • Applied indices. Hour markers fixed to the dial rather than printed.
  • Lume. Luminous material on the hands and dial. Older watches used tritium, and Seiko developed LumiBrite.
  • Tropical dial. A dial that has faded to brown with age, often valued by collectors.
  • Service dial. A replacement dial fitted during servicing.

Movements

  • Calibre. A movement model, such as Seiko's 6139.
  • Automatic. A mechanical movement wound by a rotor as the wrist moves.
  • Hand wound. A mechanical movement wound by the crown.
  • Quartz. A battery powered movement regulated by a quartz crystal.
  • Spring Drive. Seiko's hybrid of a mainspring and electronic regulation, with a smoothly gliding seconds hand.
  • Eco-Drive and Kinetic. Citizen's light powered and Seiko's motion powered quartz systems.
  • Hi-Beat. A high frequency movement, typically 36,000 vibrations an hour.
  • Jewels. Synthetic rubies used as bearings in a movement.

Complications

  • Chronograph. A stopwatch function.
  • GMT. A second time zone, usually on a 24 hour hand.
  • Day-date. A display of both day and date.
  • Power reserve. An indicator of the remaining running time.
  • Tourbillon. A rotating cage for the escapement, made to counter the effects of gravity.

Condition and history

  • Overhaul. A full service, abbreviated OH in Japanese descriptions.
  • Polished. A case that has been refinished, which can soften its original lines.
  • NOS. New old stock, unworn though old.
  • Full set. The watch with its box, papers and accessories.
  • Seikihin. A watch imported through a brand's official Japanese distribution, as opposed to a parallel import.

Related references

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