Identify real sterling silver is by its authenticating mark. When genuine silver is crafted, it is often engraved with a marking such as 9.25, Sterling, Sterling 925, or S/S. On jewelry, this marking is typically found on the clasp; on flatware, the marking is found on the underside of the utensil. Items without the sterling silver marking are rarely genuine silver.
Examine the item's coloring closely. Genuine silver is typically less shiny and cooler in tone than silver plate. If you see places where the silver appears to have worn away or flaked off, the item is probably not sterling silver.
Use a soft, light-colored cloth to rub the item. If the cloth shows black marks, the item is probably sterling silver. This is because real silver oxidizes and tarnishes when exposed to air, and the tarnish is rubbed off onto the cloth when polished.
Take the item to a jewelry store (http://www.ehow.com/
or pawn shop, and ask to have the item tested with nitric acid. This harsh industrial chemical will discolor non-silver materials because of their high copper content. Because the nitric acid will leave a permanent green spot on any silver-plated items, be sure to have the substance applied in a non-conspicuous spot.
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