Sometimes the mistakes can turn out to be beautiful. I melted my own white gold in a crucible and for some reason a tiny speck of a palladium component didn't melt properly (at least that is what I think happened). After casting a small bullion it was milled, bent and forged into a ring. When I started filing down the sides to measurement this appeared. The side of the ring is less than 2.2 mm in height so this fine line is barely visible. It will vanish from sight as the ring get it's final coating and polish (It is visible when the surface is rough but the eye hardly catches it when mirror-finished). Yet it will remain there forever, hidden. I love it, I wish I knew how to repeat this "mistake". I will try sometime but for now it will have to wait.