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Learn about the Colors Of Gold
Pure (or Fine or 24 carat) gold has a lovely warm rich yellow color that
is highly prized. It is actually an orange shade of yellow. Unlike other
precious metals, gold Jewelry can be produced in various alloys of gold,
known as the carat/karat gold's, in a range of colors from white to yellow
and through to red. In addition, it is possible to achieve other special
colors such as blue, black and purple. So how is it possible to change the
intrinsic color of gold? [An alloy is just a mixture of two or more metals;
e.g. brass is an alloy of copper and zinc.]
The simple answer is that it is like an artist mixing his paints to obtain
various hues. Every schoolboy (and girl) knows that mixing yellow and blue
produces green and mixing yellow and red produces pink or rose. With metals,
we only have the choice of mixing yellow (gold) with red (copper) or
white/grey (all other pure metals). So for the carat gold's, we can maintain
yellow at the medium and low carats by balancing the amount of copper and
silver plus zinc alloyed into the gold. If we add more copper than silver,
then we get redder shades and adding more silver or other metals than copper
gives us paler colors and even white.
However, we should note that, for a given carats of gold, varying the color
also changes other properties, such as hardness and strength. We should also
note that we can obtain a wider variation in color as we lower the carats.
This is all explained in more detail in the section on gold jewelry
alloys. White gold's, in practice, are a little more
complex since the whitening - or bleaching - effect of different metals on
gold varies: see the section on white gold's.
The special colors such as blue, black and purple are obtained by quite
different approaches, either as special metal compounds or by surface
treatments to obtain a patina. This is explained in the section on special
colors.
White Gold's What are they? Are they a special form of gold? Answers to the common questions on white gold's.
Colored Carat Alloys How color can be varied in carat alloys.
Special Gold Colors Making blue, black and purple gold.
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