Should I clean my coins?
The short answer is "NO!" Cleaning a coin often presents an enigma. A coin that has circulated and shows signs of wear has an altered appearance if it has been cleaned. In essence, what you would have is a coin that is bright but worn. Generally, a coin will lose some of its value after being cleaned. Most experienced numismatists are able to spot a cleaned coin fairly easily. If a coin is so corroded that it is unrecognizable, you may try a solution of very mild dish soap and distilled water. Rinse the coin thoroughly with distilled water and allow the coin to air dry otherwise you should leave coin cleaning to professional services such as NCS.