When buying gold jewelry, always look for the karat mark. All other things being equal, the higher the karat, the more expensive the piece. In the United States, 14-karat gold is the most common degree of fineness. Nothing less than 10 karats can legally be marked or sold as gold jewelry in the U.S.

Always look for the karat mark or "k" that appears on the back of the piece. By U.S. law, if a karat mark appears you should also see the manufacturer's trademark to assure you that the karat marking is accurate.