Breguet overcoil

Sometimes referred to as a "Breguet spiral", it controls the rate at which the mainspring unwinds.

Colour

A gem is most often chosen for its colour. The diamond has its own internationally recognized colour grading scale, defined by professional bodies. See fancy colour. Fancy colours...

Day

Period between the rising and setting of the Sun. A 24-hour interval, determined by the Earth's rotation on its axis.

Enamellist

A person who creates enamelwork.

Faceting

The cutting and polishing of the flat surfaces of a gem.

GIA

Gemological Institute of America.

Heart-shaped

A type of brilliant cut that is perfect for romantic and special occasions. Correctly executed, a heart-shaped diamond has good fire and brilliance. It has 54 facets and a culet.

Isochronism

The property of being isochronal.The science of timing lies in achieving isochronism of the regulating organ of a timekeeping instrument. The principal factors that can impair a balance's...

Jewels

International term for the rubies in a watch movement.

Karrusel

A device similar to the tourbillon, the difference being that the cage is driven by the third wheel. Invented by Bonnicksen, a Danish watchmaker established in London.See complication.

Lathe

A machine-tool that rotates a workpiece while applying a cutting tool to give the piece the required shape. The lathe, with its multiple accessories, is the traditional watchmaker's most versatile...

Motion work

The gears under the dial that transfer the rotation of the cannon pinion to the hour wheel.

Natural pearl

A natural pearl is also called an oriental pearl. This pearl is formed by an oyster, freshwater mussel or other mollusc as a reaction to a tiny invading object that happened to be caught inside...

Oval

A brilliant cut with an oval rather than round girdle (55 facets). Invented in the 1960s, it is increasingly popular for solitaire engagement rings or as a centre-stone surrounded by two...

Pin

An articulated metal catch that is inserted in a hole in the leather strap then secured by the buckle. The majority of belts fasten this way. A watch can be said to have a pin buckle.

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...

Regulating parts

The regulating organ (balance and spring) with the escapement.

Sodalite

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

Trueing calipers

A tool used to calibrate certain parts.

Universal hour

One twenty-fourth of the universal day which begins at midnight at the Prime Meridian at Greenwich. Following the 1884 International Meridian Conference in Washington, the Earth was divided...

Vibration

Movement of a pendulum or oscillating body between two extreme positions (A' and A''). The balance of a mechanical watch generally makes five vibrations per second, equivalent to 18,000...

Wind

The action of tightening the mainspring coiled inside the barrel by means of the winding crown (in a hand-wound watch) or the rotor (in a self-winding watch).

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...