The gold clay itself fires at a higher temp, Art Clay Gold at 1830F
for 1 hour, and I believe PMC gold fires for 2 hours. This is above
the melting point of silver, which is at 1761F. The only way we
metal clay artists can fire gold on silver is to use the gold paints,
either Aura 22 or Accent Gold for Silver. Both can be painted onto
fine silver after firing, but the temperatures they're fired at
would firescale sterling to a degree that, I believe, would negate
their use in your case.
We also use Art Clay Gold as a paste onto Art Clay Silver unfired to
be torch fired and burnished in a manner similar to keum bu. So,
based on what you seem to want to do with it, it doesn't look like
it will work for you.
Art Clay World, USA, Inc.