Coin history
Why cleaning coins hurts their value
Many people try to clean old coins to make them look new. Scrubbing, polishing or dipping in a cleaner leaves tiny scratches and changes the original surface.
Collectors can usually tell a cleaned coin from an original one. A cleaned coin often sells for less than an uncleaned coin of the same grade.
If you own an old coin, the safest choice is to leave it as found and store it in an inert holder.