Watch Terminology

Watches are technological wonders. They have so many working parts that understanding the technology and the terminology will help you find the perfect watch for you and your budget. Use the terminology guide below and, for a complete watch glossary, visit the Interactive Watch Guide at, the online source for fine jewelry and timepieces shopping tips and trends.

Bezel: The ring that surrounds the watch face, holding the glass covering, or crystal, in place. It can be stationary or rotating or have special functions, like indicating minutes on a diving watch. 

Case: The housing of the watch’s movement.

Watch cases are made from a wide variety of materials, including precious metals (karat gold, platinum, silver), brass, steel, titanium, ceramic, and durable plastic. With metal alloy cases, look for the identifying stamp on the case back. 

Chronograph: A stopwatch that measures continuous or discontinuous intervals of time.

The chronograph can be started, stopped and reset at will by way of push buttons. When used in conjunction with specialized scales on the watch face, chronographs can perform many different functions like calculating speeds, distances and altitudes. 

Chronometer: A chronometer is a movement that has received a certificate after passing a series of stringent tests that prove it can measure time precisely under various conditions. The most renowned official testing organization for chronometers is the Swiss C.O.S.C., or Controle Officiel Suisse des Chronometres. 

Crown: The knob outside of the case used to adjust time and to wind a mechanical watch.

Crystal: The transparent covering that protects a watch’s face.

Watch crystals are made of many different materials, the most common being acrylic, mineral and synthetic sapphire. Acrylic crystals are the least expensive and are composed of a lightweight hardened plastic. Mineral crystals are made from a variety of different minerals that are processed to produce a very hard and clear material suitable for watches. The most expensive and durable crystal is made of synthetic sapphire. Grown in a laboratory, synthetic sapphire crystals are incredibly hard (9.0 on the Mohs Hardness Scale) and are shock-resistant and scratchproof. You’ll find synthetic sapphire crystal on the finest watches made today. 

Guilloche: An engraving technique on the dial of the watch, in which a very precise, intricate, repetitive pattern or design is mechanically etched into an underlying material with very fine detail. 

Perpetual Calendar: A calendar that automatically adjusts for the varying lengths of months (28, 29, 30, and 31) and for leap years. 

Shock Resistance: As defined by U.S. government regulation, a watch’s ability to withstand an impact equal to that of being dropped onto a wooden floor from a height of three feet.

Tachometer/Tachymeter: A scale, usually located on or near the bezel of a watch, that measures the speed at which the wearer has traveled over a measured distance. 

Water Resistance: A watch’s ability to withstand water pressure to a stated depth. Watches marked as “water resistant” without a depth indication are designed to withstand splashes of water only. Watches with high levels of water resistance will reflect this by stating the number of meters the watch is resistant to (usually between 50-200 meters) on the dial or back of the case. This resistance is indicated in ATM, or atmospheres, with is a unit of measure for pressure. A smart shopper will match their needs and personal wearing habits to the right level of water resistance. Review the chart of the most common ratings.