Your question about PureGold being an alloy and still pure gold
is a good one. You are correct, if it is pure gold then it
cannot be an alloy but, in reality, all gold is an alloy. It
just depends on how pure pure gold actually is. What is being
sold today under the name “PureGold” is a microalloy. It is
0.9985 pure and therefore can be legally hallmarked 24K in the
US and in most other countries in the world. There are two
other elements added to the starting material, 0.9999 pure gold,
to harden it. The result is a microalloy that can be work
hardened and the age hardened to a final hardness of 176
Vickers. This is equivalent to the hardness of 18K gold. The
color is the same as .9999 gold but the pieces produced wear
like 18K gold.
As others have mentioned, PureGold is available in two
microalloys, PureGold-A and PureGold-C. PureGold-A is designed
for maximum hardness through cold work and age hardening.
PureGold-C is designed to provide increased hardness when used
in the lost wax casting process. It is also hardened with an
age hardening process.
Further details on working with these alloys is available from:
El Sobrante, CA 94803