Publicité
Les langues disponibles
Les langues disponibles
Glossary
A tachymeter is a graduated scale indicating the average speed
based on the time taken to cover a one-kilometre distance.
In practice, the chronograph is stopped as soon as the 1,000-metre
distance has been covered and the average speed is read off around
the rim of the dial by means of the chronograph seconds hand.
Precious metals
The precious metals most used in watchmaking and jewellery are gold
and platinum. Gold has the specific property of being unalterable, as
well as malleable and ductile (meaning it can be drawn out without
breaking). Gold is not used in its pure state (999.9/1000 or 24-carat
standard of fineness), but is instead alloyed with other metals so as
to lessen its malleability and to modify its colour.
The gold alloys used in watchmaking and jewellery are thus
composed of 75% gold and 25% other metals.
These other metals are copper, silver and palladium, in proportions
varying according to the desired colour.
• Yellow gold: 75% gold, 16% silver, 9% copper
• Rose gold: 75% gold, 5% silver, 20% copper
• White gold: 75% gold, 4% silver, 4% copper, 17% palladium
As far as terminology is concerned, the word "gold" is reserved for
alloys with standards of fineness corresponding to 0.916 (22 carats)
and 0.750 (18 carats). As for platinum, the alloy used in watchmaking
and jewellery is composed of platinum (95%) and palladium (5%).
11
Publicité
