I think that for you, I shall show my Canadian Bison coins! I love the Bison/American Buffalo which is so iconic. It was for that reason that I got the coins. At that time, the coins of RMC were notorious for developing milk spots. So I had my Bison coins blackened. They came out so beautiful. I will try find them in storage then show it here on steemit for you. Stack on @bitcoinman!
I would love to see them , and this blackened business is unheard of for me will do some research, I can definitely see what you mean about the milk spots, see it on a few of their coins