» Beading Definition: Tarnish
When metals tarnish (discolor with grey, brown or black spots or streaks) a thin layer of the metal is actually combining with oxygen, sulfur or other chemicals in the air or water to form oxides of the base metal. The most common tarnishing is caused by the simple contact of Sterling Silver with air, most commonly in the form of a grey-blue oxide. Items that have been plated with silver are plated with .999 fine silver (not Sterling Silver), which forms a yellow-tan oxide. Protective coatings are often applied to metal parts in an attempt to inhibit this process. They can be more or less effective depending on how successfully they isolate the metal from contact with other substances, including contact with the skin. These coatings usually have a short life and are easily scratched or worn.