To Clean Uncirculated Copper Coins, you have to soak the coin in grape oil or olive oil. You need to wait a few days for results. After that, Pour one pint of distilled water into the plastic container and mix in one tbsp. of dish washing liquid. You should Place the coin in the solution and allow it to soak for several minutes. Then, Cover both sides of the coin with petroleum jelly and apply the coating with cotton swabs. Next, Use distilled water to rinse off coins that have just been cleaned.