Even though we never clean coins unneccesarily, we occasionaly get it wrong, and end up with a worse-looking coin after we have cleaned it. Because gold is a noble metal, it is unlikely to become discoloured. You may even brush it gently with a soft brush. Be careful, if there is any grit present it will make minute scratches on the surface. Cleaning Silver Coins.
Silver acquires a tone through tarnishing.
A pleasant, even tone can enhance the appearance and desirability of an old silver coin. Do not clean any silver coin with this type of toning. If a silver coin is so dark brown or black that its design can hardly be seen, then it may , be worth dipping, usaully in a proprietary solution, such as Goddards's Silver Dip. Whatever you do, do not use any abrasive paste or cloth. Warm soapy water may also be used.