Jewelry allergy is a common cause of contact allergic dermatitis. Most jewelry allergy is caused by the metal nickel (see nickel allergy) which is used in the manufacture of precious metal alloys. In less expensive jewelry, nickel is often used in the base metal which is then plated with gold or silver. Many people who believe that they are allergic to gold or silver jewelry are actually allergic to nickel, which can occur as a trace element in gold or silver or has been used in the manufacture of gold jewelry to whiten and/or strengthen the piece. In affected individuals, dermatitis develops in places where nickel-containing metal is touching the skin. The most common sites of jewelry allergy are the earlobes , the fingers (from rings), and around the neck ; the affected areas become intensely itchy and may become red and blistered or dry, thickened and pigmented Sometimes the dermatitis later affects areas that are not in contact with jewelry, particularly the hands. Pompholyx is a blistering type of hand dermatitis that is prevalent in people with a previous history of jewelry allergy, and may be due to contact with other sources of nickel such as coins and keys.