improperly cleaned coins. He told me recognizing cleaned coins can be difficult at first but that it gets easier with practice. I told him that I could never identify cleaned coins and he said that when a coin is cleaned improperly there is a very very thin surface film of mint luster that is removed which will change a coin’s luster and that there is no way to repair or replace it (aside from melting the coin down and reminting it). Is this true? Is there really something on the very surface of a coin that is permanently removed with improper cleaning and can be detected because the luster will look different without it? Is that why some coins have a cartwheel luster? Im trying to learn to identify cleaned coins for when I start buying raw coins.