Amplitude

The distance between the two extreme points of a movement or periodic phenomenon (a angle).

Bar

Unit of measure to indicate a watch's water-resistance, specifically its capacity to resist pressure, based on standard atmospheric pressure defined as 101.325 kilopascals (kPa) equivalent to...

Clock

Any device (water clock, candle clock, sundial, sandglass, mechanical clock, etc.) whose function is to indicate the time. Today, it refers exclusively to a non-portable mechanism intended to work...

Dumortierite

A blue to violet ornamental stone silicate mineral that is used as used for watch dials. Dumortierite has a hardness of 7 - 8.5 and a specific gravity of 3.3 - 3.4.

Enamelwork

The result of applying enamel. Since the seventeenth century, watch cases and dials have produced some masterpieces of enamelwork.

Faceting

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

Girdle

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

Hertz (Hz)

A unit of frequency of a periodic phenomenon equal to one cycle per second.

Index for flat balance springs

An index that is often fitted with a screw or cam so that it can be adjusted by a very small amount for fine-tuning. The spring passes through the space between the curb pin and the boot.

Jasper

An opaque, ornamental stone found in many colours, including white, brown, yellow, red, and green. It is often striped, speckled, and multi-coloured and is used in watch making as a dial. Jasper...

Labradorite

A variety of plagioclase feldspar that has a greyish background with flashes of colour called labradorescence. It is used as watch dials. Labradorite has a hardness of 6 to 6.5 and a specific...

Marker

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

Nephrite

A family of the jade group of ornamental gemstones. Nephrite is slightly softer that jadeite and is often veined.

Oiling

A process used for enhancing a gemstone's colour and transparency. Gemstones that have fissures that touch the surface are often oiled; emeralds are an example.

Pavilion

In a cut stone, the part below the girdle (for diamonds) or rondiste (for coloured stones).

Quartz oscillator

The regulating organ in a quartz clock or watch.

Railroad

A minute scale on a dial that resembles a railway track.

Set (to)

To secure a stone of any cut or size in metal. The stone and the metal are generally precious. The jeweller prepares the hole in which the stone is seated.

Tweezers

Small pincers for picking up and handling delicate parts.

Universal Time (UT)

Since 1972, a continuation of Greenwich Mean Time (GMT) which is mean solar time at the Greenwich meridian. Universal Time (UT) is a measurement of time based on the Earth's...

Vagues de Genève

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

Wheel-cutting engine

A machine for cutting the required number of teeth into an unfinished gear after marking the position of each tooth with a dividing plate.

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.