Looking a lot better. Seems some of the white is still there. As long as you don;t let acetone evaporate in the coin, its safe to keep it in there. Just saying if it were mine I would put it in linger to see if the white all comes off of it. If not this, then Xylene next.
Also, just what I do, put it in a covered container. I use a baby food jar with lid. That way the acetone won't evaporate.