Alarm

A pocket watch, wristwatch or clock that automatically sounds at a preset time. The alarm function regained in popularity with the launch, by Eterna in 1908, of a wristwatch with alarm.

Brilliant cut

A round diamond that is cut with 57 or 58 facets or 32 facets + plus the largest facet called the table, 24 are below. The 58th facet is optional and is polished at the point of the diamond.

Cloud

A cluster of tiny inclusions in some gemstones that has a milky appearance.

Daylight Saving Time

Legal time in certain countries that is one hour ahead of winter time, itself one hour ahead of solar time.

Enamellist

A person who creates enamelwork.

Finishing (Finissage)

The final operation in a process. On a watch case, the last stage in assembling the parts so that they function.

Girdle

The girdle is the widest perimeter of a gemstone that separates the top (crown) and the bottom (pavilion) of a cut gem.

Horology

The science of measuring time.

Integrated circuit

A group of electronic components and their connections, performing one or more functions. Integrated circuits for watches measure just a few square millimetres.

Jewels

The international term for the jewels (rubies) in a watch movement that are used as bearings for pivots to reduce friction. The movement of a quality watch has between 15 and 21 jewels.

Knot

A raised mineral inclusion in a diamond found at the surface.

Micron

A metric unit of length equal to one thousandth of a millimetre or one millionth of a metre. The watch industry often expresses tolerances in microns.

Nacre

The iridescent substance secreted by molluscs around a foreign object. Pearls and cultured pearls are covered with nacre by certain species of oysters and mussels.

Oscillator

A device such as a pendulum or balance that produces the oscillations that divide time into equal units: a balance spring in a mechanical watch; a quartz in a quartz watch.

Pavé

A group of gems set closely together to cover an entire surface.

Quartz

Silicon dioxide. Also called rock crystal. Quartz has the specific property of vibrating at a very high frequency (32 MHz) placed under electric current. Under certain conditions, it...

Repeater

A watch that strikes the hour on demand by activating a pushpiece or a slide (bolt). There are several types of repeater: Half-quarter and quarter...

Screw

A fastening comprising a cylindrical shaft, grooved along part or all its length, and a head with a slot for the screwdriver.

Time zone

In order to standardise time measurement in each country, since 1883 the Earth has been divided into twenty-four time zones, the first of which is intersected by the Greenwich meridian,...

Under-dial work

Collective term for the mechanisms, such as for striking, a calendar or motionwork, between the dial and the dial plate.

Vane

Uses air friction to slow a moving part, for example the arm on a gravity escapement.

Watch

A portable timepiece that functions in all positions. A watch comprises three essential parts: The movement made up of the different mechanical components required to keep...

Year

A four-digit indication of the current year that changes automatically at midnight on December 31st.

Zinc

A metal applied by electrodeposition (electroplating) to protect iron and steel.