À tact watch

Repeater watch (see complication) in which hammer and bell are replaced by a sharp pin which protrudes from the case to prick the finger once for each hour.A type of watch made after...

Brace (Bridle)

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

Case

Container that protects the watch movement from dust, damp and knocks. The case is part of the watch's appearance and, influenced by fashions and buyers' personal taste, must have visual...

Display lighting

A means of lighting the dial and/or hands, using either an electroluminscent substance or an electrical system.

Engraving

The art of forming patterns either by hand, using a graver, or by machine such as a rose engine.

Frame

J.C. Nicolet defines the frame as the chassis inside which all the parts of the watch movement are housed. A clock frame comprises two plates whereas a watch, and in particular wristwatch,...

Grande complication

See complication.

Horology

The science of measuring time.

Impulse

In a lever escapement, the action of the escape-wheel tooth on the impulse-face of the pallet.

Jumping hour

A means of display in which the hour, shown through an aperture, instantly changes every 60 minutes.

Knot

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

LumiNova®

A new-generation luminous substance, used to coat hands and numerals. It stores light which it then emits in the dark causing the hands and numerals to glow and continue to be visible. Previously,...

Malachite

An opaque ornamental stone with striations of deep and light green- Used by the ancient Egyptians in jewellery, today it is sometimes found on watch dials. Malachite has a hardness of 4 and a...

Nickel silver (German silver)

A silver-white alloy of copper, nickel and zinc developed in France circa 1820 by Maillot and Chorier from whom it takes its name.

Opale

An amorphous gemstone that shows the spectral colours called fire on either a white or black background. An orange variety called Fire Opal comes from Mexico and does not always have the fire of...

Platinum

A heavy metal, greyish white, that is highly resistant to corrosion and difficult to work with.Jewellery and watch cases can be made from platinum.

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.

Spinel

A gemstone found in every pastel colour. The red variety was often mistaken for ruby. It has a hardness of 8, a specific gravity of 3.58-4.06, and a refractive index of 1.72.

Timer

A watchmaker who carries out timing operations.

Under-dial work

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

Water-Resistant

Describes a watch which, in theory, will not let in water at a depth of up to 3 atm or 30 metres. See Waterproof

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.