Aperture

A small opening in the dial. In an aperture watch, various indications such as the month, moon phase, day, date, hour, minute, etc. are visible through these openings.

Brace (Bridle)

Part that holds or retains. Clamp, Winding-stem brace, Mainspring bridle, Slip spring, pivoting brace

Combustion clock

Graduated candles or oil clocks whose diminishing level of fuel indicates how much time has passed.

Dichroism

The property of certain gemstones that show more than one shade of colour when viewed from different angles. Many gemstones, for example rubies, sapphires and tourmaline, are naturally...

Engine turn

To cut metal with decorative engraving by hand or using an engine turning machine.

Fluting

Grooves cut the length of a rod, pillar or button. Fluting makes it easier to grip the winding-crown.

Gold

Gold has seduced the world with its beauty, but also because not even acid can alter its natural properties. An estimated 130,000 tons have been extracted from the earth since prehistoric times,...

Hand-setting

The action of adjusting a watch's hands to the time shown on a reference clock.

Inverted calibre

calibre whose dial is on the side with the bridges and geartrain rather than on the bottom-plate side

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.

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 -...

Lunation

The period of time elapsing between two successive new moons.

Marine chronometer

Traditionally, "marine chronometer" refers to a large watch for keeping time onboard ship. In the latter years of the eighteenth century, the term was extended to mean a...

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.

Oil sink

A cavity in bearings for a drop of oil.

Planing machine

Until the end of the eighteenth century, watchmakers would plane teeth and leaves on wheels and pinions by hand, first dividing them with special files. Later, for around a century, a planing...

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...

Sodalite

Sodalite has a dark blue background with inclusions of white, grey, pink or green. It is used as watch dials.

Tritium

A radioluminescent substance containing tritium that is used to coat the indicators on timekeeping devices so they can be read in the dark.

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.

World time

Describes a watch that indicates, usually by means of subdials surrounding the main dial, local time (true solar time) in different world cities. Often these cities were chosen for their political...

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...