Assortiment

French term for the three parts of the escapement (escape-wheel, lever and roller). Generally, specialist companies supply watchmakers with the lever assortment.

Back

In a watch case, the cover, transparent or not, opposite the dial.

Calibre

Synonym of size. Sully used this term circa 1715 to denote the layout and dimensions of the different movement pillars, wheels, barrel, etc. Since then "calibre" has been used to...

Dynamograph

Indicates the amount of tension in the mainspring so as to maintain it within ideal limits. Developed for watches by Audemars Piguet, it indicates the torque supplied by the mainspring. As long as...

Electroplating

A plating technique using electrodeposition.

Finishing (Finissage)

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

Green garnet

Demantoid garnets, a green, and very lustrous type of garnet. They have characteristic inclusions that look like horsetails. Demantoid garnets has a hardness of 6-7 and a specific gravity of 3.8 -...

Horn

That part of a watch case to which the strap is attached. Horns come in various shapes and are attached to the case middle.

Intermediate wheel

A small toothed wheel, part of the hand-setting mechanism.

Jewel

To set or push fit jewels (ruby bearings) in a watch movement.

Knot

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

Light-Emitting Diode (LED)

A segmented luminous source used to display numerals on electronic digital watches. Operated by a push-button.

Movement

The duly-assembled organs and mechanisms of a watch, meaning the winding and hand-setting mechanism, the mainspring, the gears, the escapement and the regulating organ (spring...

Nephrite

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

Perpetual calendar (watch)

A watch whose perpetual calendar (see complication) automatically takes the number of days in the month into account: 30 or 31 and the 28 or 29 days of February for ordinary and leap years. Unless...

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...

Refractive index

The ratio of the speed of light in air and the speed of light in an optically denser medium. Each gemstone has a specific refractive index that, when legible, can identify it.

Skeleton movement

A movement whose plate and bridges have been cut away to expose the wheels, leaving only the substance which the watch needs to function. The movement is placed between two sapphire crystals to be...

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.

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...

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.