Argand burner

An oil lamp once used by watchmakers as lighting.

Bridge

A metal plate under which the pivots of the wheels and pinions turn. Both ends of the bridge are secured to the plate by screws. Generally a bridge is named according to its function,...

Corundum

A species or family of gemstones that includes ruby or sapphire, depending on the colour of the gemstone (which in turn depends on the trace elements present) Corundum is a very hard mineral...

Diffusion treated

A treatment used on gemstones to enhance their colour. The diffusion process only colours the outer surface of the stone, The CIBJO prohibits the sale of diffusion treated gemstones without...

Escapement

A mechanism that is fitted between the gears and the regulating organ. Its function is to suspend the gears' motion at regular intervals and to supply energy to the balance. The main types...

Fracture

A break in a gemstone.

Goldsmith

A craftsman who produces decorative objects in precious metals, as well as in pewter and copper.

Hour-wheel

The wheel that carries the hour hand.

Inverted calibre

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

Jeweller

In its original, eighteenth-century meaning, a jeweller is an expert in the art of mounting precious stones in gold, silver and, later, platinum so as to bring out their full beauty and sparkle....

Lapidary

A craftsman who cuts, polishes and sells coloured and precious stones. A lapidary who specializes in diamonds is called a diamond-cutter.

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.

Oil sink

A cavity in bearings for a drop of oil.

Point

A point is a hundredth of a carat or 0.01 ct.

Quartz oscillator

The regulating organ in a quartz clock or watch.

Rhodochrosite

An ornamental gemstone that is pink with white veins. As with most ornamental gemstones it is used for watch dials.

Secret spring

A spring that releases the cover on a hunter watch case.

Turning arbor

Slightly tapered arbor in tempered steel for turning the hour wheel.

Under-dial work

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

Vermeil

Silver covered with a thin layer of gold.

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.

Zinc

A metal applied by electrodeposition (electroplating) to protect iron and steel.