PLATINUM.
Platinum
has been used for thousand of years, but it was not
recognized as a chemical element until 1735. Of the three
precious metals-gold, silver, and platinum does not tarnish
when exposed to the atmosphere, unlike silver. It is silvery
gray, gray, gray white , or white in colour, opaque, and has
a metallic lustre. It is slightly more dense as silver.
Early jewellers had difficulty achieving the 1,773oC
(3,223oF) needed to melt platinum: it was not
until the 1920s that the technology was developed
sufficiently to work this precious metal.
Occurrence
Platinum
forms in igneous rocks, usually as ores in which the grains
of platinum are often too minute to be seen with the naked
eye. It may also occur in secondary "placer"
deposits in river sands and gravels, and glacial
deposits-usually as grains, more rarely as nuggets. The
mainoccurences of platinum have been in South Africa, Canada
(Sudbury), the USA (Alaska), Russia (the river Perm and
other rivers running down from the Urals), Australia,
Colombia, and Peru.
REMARK
Although
nuggets had been set in rings before 1920, most platinum
jewellery dates from after this time. Soft and easy to work,
platinum is often fashioned into quite intricate designs.
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RING
AND
EARRING
SUITE
This modern
suit is set with square-cut precious stones in
all the colours of the rainbow |
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AQUAMARINE
RING
Platinum
provides a cool setting for this ice-blue
pendeloque cut aquamarine and its twenty
diamonds. |
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FILIGREE
NECKLACE
Like gold and
silver, platinum is quite a soft material,
making it ideal for the sort of intricate
working seen in this necklace. Unlike silver,
platinum does not tarnish when exposed to the
atmosphere
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NECKLACE WITH
DIAMONDS
Platinum is a
perfect, if very expensive, setting for cut
diamonds, as the colours complement each other
well. |
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