can anyone tell me what alloy is used to create Rose Gold ?
Copper is what gives a rose or red gold alloy it's color. An 18K red
gold made of just gold and copper will be a very "red" gold color,
though it needs careful handling when heating or annealing to avoid
it becoming very brittle and hard (It must be quenched from above
about 800 degrees F. Don't slow cool or air cool it. Alcohol
quenching avoids the possibility of stress cracks from quenching.
If a straight gold/copper color is too rich, add silver to tone down
the color. The more silver you add, the more the color moves to the
standard gold alloy colors. A little silver with mostly copper in the
alloy (mixed of course with the desired percentage of gold for the
karat you're making) still gives a nice rose color, and helps avoid
those problems with a brittle structure.
There's no one exact formula, since "rose gold" covers a range of
colors, but the basic alloy is simply copper, or copper with a
variable amount of silver.
Some commercial rose golds may add things like small amounts of zinc
or other deoxidizers to make it more castable, but these need to be
small additions or they affect the color negatively...