I've tried cleaning the nickel with a Q-tip. The face is darker than the rest of the coin, nothing comes off onto the Q-tip. The coin does not have a dull finish on the front. On the back it also had some discoloration over the entire coin. I've looked at it with a pair of high power magnifying glasses and it really looks like it's just part of the coin. It's cool looking - I'll just add it to my collection. Thanks everyone for your input - greatly appreciated.