A simple cleaning can be cleaned but no on jewelry! But what is actually "run"?
Silver jewelry starts in principle what is thus also a feature for the authenticity. Also alloys of 333 and 375 gold start, albeit in a much lesser degree. This means that the jewelry with the in the air contained sulfur oxidizes and then unsightly yellowish to black. How strong is a gem, depends on various factors, such as composition of the alloy composition of the air, other environmental factors (chemicals, cosmetics, medicines) and the composition of the natural acid mantle of the skin.
It takes a plastic bowl (not metal), with boiling water, it solves conventional table salt on (up to 1 liter of water, 200 gr. Salt), lay a piece ofaluminum foil on the bottom of the bowl and placed the jewels (only without stone and Pearl trim) on the aluminium foil. The jewelry must remain in the water until loosened the black surface and shall be liable on the slide. Finally rinse with clear water and dry.