Anyway I had it soaking in a cup of distilled water for about 3-4 weeks but it didn’t seem to do much. I had tried over the weeks picking at it with a toothpick but that wasn’t getting anything off and no luck with a toothbrush either. Well today I took the coin out of the water and this time tired using a metal pin to scrape it off. I had success and this was now starting to get the stuff off it but to my horror I discovered that I had scratched the coin So I pretty much ruined it and made it look ugly. There’s no way I’m keeping it so that’s like $90 down the drain. But to be fair the toothpicks and brushes weren’t doing anything so trying a pin seemed like the logical next step. It’s just a shame.