Red gold turning yellow in mokume with sterling

Recently and once a few months ago, I had issues with 14k red gold
turning yellow in red gold and sterling mokume. The entire line of
red gold didn’t turn yellow, just the outside edges of the lines, so
where there was a red line, there is a yellow line, red line, then
yellow line. I’m not getting the temperature that high, I don’t
think. I was using easy solders, but the red gold seems to liquify
or the edges turn yellow. I’m not sure if the copper is being
depleted at the surface or if there is a new alloy being formed
between the red gold and sterling, which looks like yellow gold. Is
there any way to reverse this or is the piece ruined?

You overheated it plain and simple. When you exceed 1435F the
sterling fuses with the red cold creating a yellow alloy.

James Binnion
James Binnion Metal Arts