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.

Balance spring

A very fine spring and the "heart" of a mechanical watch. Its ends are affixed to the balance and the balance-cock. Its elasticity allows the balance to make regular oscillations. Its length, and...

Complication

Any function other than the indication of hours, minutes and seconds, regardless of whether the mechanism is hand-wound or self-winding, mechanical or electronic, and of movement height. The...

Disconnect

To interrupt the transmission of movement between two parts. The winding mechanism is an example of a mechanism whose parts are connected and disconnected.

Emerald

The saturated green variety of the Beryl family. Its colour is due to minute traces of chromium or sometimes vanadium. Inclusions in emerald are called jardins from the French word for garden....

Frequency

The number of oscillations per second, measured in Hertz. The balance makes a to-and-fro movement at a given frequency (two vibrations). The higher the frequency, the more accurate the watch:...

Grain

A unit of weight for fine pearls: one grain equals a quarter of a carat or 0.05 grams. In stone-setting, the grain is a shaving of metal lifted from the mount and bent over the stone to...

Hammer

A metal part that strikes gongs causing them to vibrate and produce sound. See...

Indicator

A watch's indicators are its dial and hands.

Jumping seconds

On a chronograph, a hand that makes one rotation every second, pausing four, five, even eight times to indicate quarters, fifths or eighths of a second. Also called foudroyante.

Kunzite

A transparent pink or light purple gemstone and is a variety of spodumene. The colour of some kunzite can be enhanced by irradiation. Kunzite has a hardness of 6-7 and a specific gravity of 3.1 -...

Large date

A date function with large numerals on two independent discs, displayed through oversized apertures. In 1994, A. Lange & Söhne displays for the first the the Large Date in the...

Marker

A symbol that replaces some or all of the numerals on a dial.

Niello

An enamel-like alloy of lead, copper, silver, sulphur and sal ammoniac (ammonium chloride). Niello paste is applied over incised gold or silver then fired in the enamellist's furnace. Excess...

Official rating certificate

A document, issued by an Observatory or an official ratings bureau, that certifies the quality of a watch which has proven, in trials, to meet with a given standard. Only a watch that has received...

Parts

The various elements used to make or repair a watch. In the latter case, these are spare parts.

Quartz oscillator

The regulating organ in a quartz clock or watch.

Secular Perpetual calendar

Devised to incorporate the specificities of the Gregorian calendar. It is perpetual because it automatically adjusts to months with 30 days and to the 28 or 29 days in February. Unlike the...

Table

The table is the large, flat facet area on the top of a cut gemstone.

Under-dial work

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

Vagues de Genève

Synonym of Côtes de Genève. A decoration of undulating lines, like waves, frequently used to embellish superior quality movements.

Water-Resistant

Describes a watch which, in theory, will not let in water at a depth of up to 3 atm or 30 metres. See Waterproof

Year

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

Zodiac

At the heart of countless legends and beliefs, since ancient times precious stones have had symbolic value. From the Jews to the Egyptians, each culture and religion has given a different meaning...