What do I do with this medal?

Blackhawk

I bought this 33mm medal/jeton reasonably without really knowing anything about it. After some research I've found reference to it being by Jean Dassier and struck in 1720. The piece has some problems as you can see, but the green verdigris or what ever it is does not appear to have ruined the coins surface to any great degree. I've tried a acetone soak with no results, and olive oil has not had any effect either. Does anyone have any information about this piece?...Would it be worth sending to NCS to see if they could remove the crud, or is the value of the piece to little to justify the expense? Any ideas on how to remove the stuff?

TwoKopeiki

I've used ammonia to remove green verdigris on copper. But you have to be careful with how much and where you apply it, because it strips the patina right off.