Silver jewelry primarily refers to items manufactured of Sterling Silver, an alloy containing 92.5% Silver combined with 7.5% Copper. As Silver is very soft and malleable, Copper is added for strength and durability. This small amount of Copper does not affect the appearance of the Silver. For jewelry to be considered “Silver” in the United States, it must – at a minimum – be Sterling Silver. Acceptable markings appearing on Sterling Silver jewelry are .925, Sterling Silver, Ster or Sterling. In addition to these marks, a manufacturer’s mark – or – registered trademark is required by Federal law.
Sometimes a process called “flashing” is used where a thin coating of .999 fine Silver is applied to Silver jewelry to improve shine. Rhodium plating can also improve the shiny appearance of Silver jewelry. In addition, jewelry referred to as vermeil is composed of Silver coated with Gold. To be considered vermeil, the base metal must be Sterling Silver and the coating must be at least 10K Gold and 2.5 micrometers in thickness. GoldFellow® purchases vermeil as Sterling Silver.
Silver jewelry, like household items made of Sterling Silver is prone to tarnish. This occurs when the Silver reacts with hydrogen sulfide or sulfur in the air. Since GoldFellow® purchases Sterling Silver Jewelry for its silver content, the condition or appearance of the piece does not affect the amount of cash for silver GoldFellow® pays.
http://en.wikipedia.org/wiki/Silver – Silver
http://en.wikipedia.org/wiki/Vermeil – Vermeil