Precious Metals - Pierre DeRoche Chrono Penta PDR 4012 Mode D'emploi

Precious metals

The precious metals most used in watchmaking and jewellery are gold and pla-
tinum. Gold has the specific property of being entirely stable, as well as malleable
and ductile (meaning it can be drawn out with breaking). Gold is not used in
its pure state (999.9/1000 or 24 carats), 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 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%).
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