How To Tell If A Coin Has been Cleaned
It is very important for aspiring coin collectors to know never to clean a coin, especially a rare coin, that you find for your collection. The surface condition of a coin is essential in indicating its value, and this value is reduced if the coin has been cleaned. For coins from the 20th century, cleaning will completely render them valueless. If an older coin, say from the 18th or 19th centuries, has been cleaned, it still may have some value due to its rarity – but it would be more valuable if its surface was still intact and if it had never been cleaned.
So how can you tell if a coin has ever been cleaned or not? The easiest way is to look for hairlines or scratches. Most careless collectors who have cleaned coins used an abrasive cleaner, which almost always leaves small scratches on the surface of the coin. Also, if you see black or dark gunk gathered around the details of the coin, it may also have been cleaned, as this gunk may be leftover cleaner. You may think that the buildup could just be from dirt and oils after years of handling, but those things to not usually build up in corners the way residue from a cleaner will.
Another sign of cleaning is the toning of an old coin. If the toning is wildly uneven or off-color, there is a good chance the coin has been cleaned. Even the most delicate cleaning will strip a coin of its outer layers and cause it to tone in an unnatural, uneven way. Also be suspicious of coins that are very old but that appear to be in great shape. Is that 1812 coin really naturally that shiny after 200 years, or has it been cleaned? Logically, even the best-kept old coin will have toned and tarnished after a long passing of time.
