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...

Beryl

A family of stones that share the same crystalline and chemical properties. Varieties include the emerald and the aquamarine.

Copper-plate

Delicate line engraving or etching on copper.

Dauphine

A type of hand in the form of an elongated triangle.

Electroplating

A plating technique using electrodeposition.

Fly-back (Retour en vol)

A function of particular use to pilots by which the chronograph hand can be reset to zero and immediately started again by pressing once on the pushpiece. Indeed, the operation of...

Glucidur (Glucydur)

A highly elastic, hard, amagnetic and corrosion-proof alloy used to make monometallic balances, escapements and balance-springs.

Hertz (Hz)

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

Irradiated (treated) diamonds

Diamonds that have been exposed to radiation in order to change their colour from yellowish to fancy yellow or blue. The change is permanent.

Jumping seconds

On a chronograph, a hand that makes one rotation every second, pausing four, five, even eight times to indicate quarters, fifths or eighths of a second. Also called foudroyante.

Lapis lazuli

A rich blue opaque gemstone often used in watch dials. It is specked with pyrite that looks like gold. Lapis has a hardness of 5.5; it has a specific gravity of 2.4 to 2.9. Lapis lazuli is not a...

Marcasite

Marcasite is a misnomer for pyrite that has been cut in shiny metallic stones. It is sometimes found on watch bracelets and cases.

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.

Onyx

A black agate that is often found as watch dials.

Pearl

An organic gem material found in oysters and mussels. Since 1913, pearls are cultured meaning that a nucleus is inserted in a farmed mollusc. There are many types of cultured pearls: Akoya...

Quartz oscillator

The regulating organ in a quartz clock or watch.

Retour en vol

A function of particular use to pilots by which the chronograph hand can be reset to zero and immediately started again by pressing once on the pushpiece. Indeed, the operation of stopping,...

Sweep seconds

Also called centre seconds. A seconds hand positioned at the centre of the main dial.

Termineur

An independent workshop or independent watchmaker assembling all or some of a watch, using parts supplied by an établisseur or manufacture.

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...

Vagues de Genève

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

Winding mechanism

The mechanism which tightens the mainspring in a watch or lifts the weights in a clock. It comprises about ten parts (see drawing). The winding and hand-setting mechanisms have nowadays...

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...