About Sterling Silver
"Sterling silver" is an international designation defined as a metal alloy (blend) containing at least 92.5% silver. The most common sterling alloy is 92.5% silver and 7.5% copper. The addition of copper adds hardness to the metal. Silver jewelry advertised as "sterling" must meet that standard. In most cases, genuine sterling silver jewelry will be stamped ".925" which indicates its 92.5% silver content.
Fine silver, usually stamped ".999," is 99.9% silver. Since silver is a soft metal, fine silver is typically used only on heavier jewelry articles, such as cuff bracelets, where flexibility is important.
Reaction with the chemicals in the environment and air causes silver to naturally oxidize. This is not a defect, but a natural property of the metal. Unplated sterling silver articles can easily be restored to their original luster by polishing with silver polishing pastes and cloths, or dipped in silver cleaning solution. Articles plated with rhodium or gold ("vermiel" or "rose-tone") are not subject to oxidation and should be cleaned with mild dish soap and a lint-free cloth.