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In this section, we discuss the various popular precious metals
from which jewelry items are manufactured:
Platinum
Platinum is the rarest metal, making it considerably more
expensive than even pure gold. Eighty-five tons of platinum is
mined annually, compared to 1,500 tons of gold. Ten tons of ore
must be mined to produce one ounce of platinum. It takes five
months to refine platinum before it can be used in jewelry.
Platinum is the purest metal. Platinum is the only precious
metal used in fine jewelry that can be 95% pure. Small amounts of
iridium and ruthenium (a metal from the platinum family) are
commonly added to platinum. The stamp will read PLAT, PT or 950.
Platinum's purity makes it the only truly hypoallergenic metal.
Platinum is also the strongest metal. It weighs 60% more than
gold and has a high resistance to heat. It is very dense and
extremely resistant to wear. Although platinum will still scratch
just like any precious metal, the scratches do not represent
material loss.
Major platinum deposits are located in South Africa and the
Soviet Union. Cartier, Faberge and Tiffany gave platinum its place
in fine jewelry. During WWII, platinum was declared a strategic
metal and its use was banned until after the war.
More on
Platinum »
Gold
Although gold is not nearly as rare as platinum, it is equally
as desirable. Gold is much less expensive than platinum, but like
platinum, it does not rust, tarnish or corrode. It takes seventeen
tons of gold ore to extract one ounce of pure gold. It then takes
three weeks to refine the metal to be used in jewelry.
In its purest form, gold is too soft to withstand the wear and
tear of everyday use. So, alloys are added to make gold more
durable. Pure gold is 24 Karat, or twenty-four parts gold. It will
be stamped 999. 14 Karat gold is fourteen parts gold and ten parts
of another alloy (usually silver, zinc or nickel), or 58% pure
gold. The stamp will read 14k or 585. 18 Karat gold is eighteen
parts gold and six parts of another alloy, or 75% pure gold. The
stamp will read 18k or 750.
Gold is naturally yellow, but you can find it in white, rose and
green. Different colors are achieved by adding different alloys.
For example, white gold is made by adding nickel and zinc and rose
gold is made by adding copper. Adding silver makes gold with a
slight greenish tint.
Sterling Silver
Sterling silver is the third precious metal. It is frequently
used in jewelry because it is relatively inexpensive, it is an
abundant metal and it is easy to form. Silver is half the weight of
platinum and is alloyed with 7.5% copper. Its stamp will read
925.
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