sterling silver turns black

Does silver tarnish? This is a tricky question, as technically, tarnishing does not occur in pure silver. However, pure silver is too soft to be used in jewelry crafting. Therefore, jewelers will often add a small quantity of copper to strengthen the silver. The resulting product is .925 sterling silver, which contains 92.5% pure silver and 7.5% copper. It is the primary material used for silver jewelry.