Thanks for the comments guys. Lots of different opinions on this one. I had no idea. Very educational though and much appreciated. Anyways to address some of your comments. Thank you for the offer Boss!! The At this point, I occasionally give my coins a mild acetone bath but not much more unless corrosion is a problem. I may investigate your method and try it out on some common wheaties! It sounds like you're on to something, and I adore your higher grade 12-s! About changing a VF coin to AU; I've got lots of coins that could use some of that magic dust!! (I assume you were kidding).. Interesting, that never even occurred to me. I'll have to look into that. Do they make it into slabs? It seems I've seen certified ones the same color. This never occurred to me either. I have been examining those two spots you mentioned, and it appears in both areas there is black foreign crud that is raised on the surface. It is not at all green, just black. Does this form as a result of cleaning? I figured they were carbon spots, or just foreign debris, or maybe early stages of corrosion. I don't really see evidence of cleaning, but I'm far from a copper expert. The color in hand is the same on both the obverse and reverse.