I've had this coin for quite a while but never really looked at it much. I'm not even sure if it is a real Roman coin, so whatever information you can give me would help. Would acetone help the green residue? This is my initial attempt at editing coin pictures, so you can critique my photo/editing skills, especially because the coin was photographed in a reflective 2x2. :smile
It is a Roman provincial bronze of Gordian III, from Metropolis in Ionia. I will leave the cleaning and other comments to others, but I will suggest that you kindly remove the coin from the flip before photographing, next time.
I'd leave the green alone. What is underneath is likely to be much uglier and this looks stable. I agree and generally say that if you don't want a photo bad enough to remove it from a flip, just don't shoot it.
