Precious metals

Silver:

Silver is a relatively ductile and very malleable metal, valued for its unique white glow.

Jewelry and silverware account for 7700 tonnes a year of the commerce. Silver’s good workability make it ideal for design work, and often means it is used to make diversified jewelry for instance; pendants, bracelets and necklaces. Silver is often alloyed with small amounts of copper to improve its mechanical properties. It is used as the gold alloy, or plating (3 to 5 microns thick for jewelery, 20 to 30 microns for silver jewels).

Gold:

This is mixed with one or more other metals to increase its rigidity, and can have white shades (white gold) or red shades (red gold), depending on the type of alloy that is used (silver, copper). The standard proportions vary from one country to another, for example, the United States and Greece are using the gold called "14K", containing 585/1 000 gold. In France, "when it comes to products containing gold, platinum, silver or palladium, the price tag must be accompanied by an indication of the precious metal used and its title expressed in thousandths "; above, a distinction was made between "gold" [18K (750/1, 000) or more] and 'gold alloy' [less than 18K (750/1, 000)].

For 18 carat gold:

* Yellow gold is in principle consisting of 75% gold, 12.5% silver and 12.5% copper.

* Rose gold is normally composed of 75% gold, 20% copper and 5% silver.

* White gold usually contains 75% gold, silver, copper and sometimes palladium.

* White gold jewelry is a term often used to refer to white gold. In France and Europe, nickel (which came once in its composition) it is now banned because it is a source of allergies. Gold “blancest” that is therefore covered with a thin layer of rhodium (gold "Rhodium"), which disappears with time, restoring a gray-yellow to gold (it is usually possible to make a new layer of rhodium in a jeweler for a a small amount of money).

* Blue Gold is an alloy of gold and iron. Using heat treatment the iron atoms appears on the surface of metal and gives it its azure oxide.

Platinum:

Very popular in jewelry, it is a chemical element with the symbol Pt.

It is a transition metal that is hard, malleable, ductile, rare and precious, with a gray-white color. Platinum is a noble metal resistant to corrosion, and it is often found associated with certain ores of copper or nickel, and more rarely in a native deposits (including South Africa).

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