When discussing jewelry that makes the skin green, copper is usually the culprit. When jewelry is made of copper, it will react with sweat, lotion and other products on the skin and oxidize. After copper is oxidized, it will react chemically, forming a green "film" on jewelry, and then transferring it to the skin.

However, copper is not always a problematic metal. Tori Dundas, founder and president of True curatorial design company, said, "You must be careful about any fashion jewelry that is not pure gold or platinum, because it may not always determine which metals are included in the alloy." "Many people have to ask about nickel and copper in particular because skin allergy to nickel is common."