DO NOT CLEAN YOUR COINS! Just like any antique piece of furniture, or painting, the original surfaces of a coin are much more desirable by collectors than altered or damaged surfaces. As a result, cleaned coins are worth significantly less money than wholly original coins. Even though a coin is dark in color, does not mean that it is less valuable. The metal in coins often oxidizes and produces a wide array of colors called toning. Some collectors hunt for wholly original coins with this type of toning.