"Steve Lusardi" wrote in message
...
There is a simple way to determine the percentage of gold on a comparison
basis. Typically 10K is 25%,14K is 50%, 18K 75%, 22K 90% gold and the rest
is alloying materials mostly of which is copper. snip--------

Close, but no cigar. Considering karat gold is defined as 24K=100% gold
content, 10K is 41.6% gold (by weight),
12K is 50% content, 14K is 58.33% content, 22K is 91.66% content. You had
it right on the 18K. In the US, it is illegal to mark gold under 10K,
but that is not true in other countries. Regards the alloying agent,
while copper tends to be the major alloying element, the color of the gold
dictates what is used, and in what proportions. Yellow gold is comprised
of silver and copper, generally with a trace of a sacrificial element to
keep the base metal from oxidizing, often times just zinc. White gold has
no copper at all, but contains nickel instead. Green gold is primarily
silver and gold. Blue comes from the addition of iron.

Harold