Sterling silver has traditionally been kept as bright and shiny as possible. However, some people enjoy the appearance of oxidized sterling silver, especially when used in jewelry. Oxidized silver has a distinctively smoky appearance. It is dull rather than shiny and may come in black or various shades of gray. Cleaning oxidized sterling silver the same way you would polish normal silver will ruin the oxidization and completely alter the appearance and style of the piece. Silver polish is especially dangerous as it is actually designed to remove oxidization and tarnish.
Pour the warm water and dishwashing liquid into a bowl big enough to hold your oxidized silver and stir or swirl gently to mix. Use only warm water in this stage; hot water can affect the oxidization.
Put your silver into the solution in your bowl.
Wait 10 to 20 minutes until any visible dirt or residue on your silver is softened.
Remove your oxidized sterling silver from the bowl.
Dry your silver gently with your soft towel. Do not rub the silver roughly with the towel, as this may remove or damage the oxidization.