A little bit about sterling silver and the proper care of it:

Pure bullion silver (.999 Fine) is too soft to make into jewelry, so an alloy is made by adding around 6-7% copper and a tiny amount of zinc or nickel. The resulting alloy is identified as .925 or "Sterling" silver. Sterling silver is a metal that is meant to be worn. Left on top of a night stand, silver will tarnish. One way to prevent silver from tarnishing between displays or wearings is to keep the jewelry in cloth pouches or Zip-closure plastic bags. A silver cloth is the best way to remove tarnish from jewelry. Over time, liquid cleaners tend to yellow the metal (although buffing will bring back the original shine). Light mechanical buffing with a soft polish-treated cloth usually works best.