Instructions
Clean off the coin entirely, careful that all dirt and grime is cleared away leaving only the metal of the coin. This will ensure that you can see the coin clearly and are certain that the date is faded or damaged in some way.
Dab the coin with olive oil or Vaseline with a Q-tip. This will help bring shine back to the coin. Often times, features can be restored to coins just hours after being dabbed with one of these substances. After you coat the coin with one of these substances, wait for several hours and then look over the coin again. It will more than likely have at least a portion of the date on it at this point.
Rub the coin down with soap and water. This clears off the oils you put on it without causing damage to the coin.
Dip the coin in club soda or vinegar, keeping it submerged for about 20 minutes to an hour. Take the coin out. At this point, the date should be visible again. Dry the coin with a blow dryer or just by leaving it in a warmly heated room for a day or so.