All of our necklaces are made from a mixture of stainless steel, 18K gold plated stainless steel, sterling silver and gold-plated sterling silver. All of these materials are excellent for their durability and non reactiveness. Waterproof, sweat proof and life proof! These pieces won't tarnish or leave your skin that horrible green colour. The 18K gold plating is applied at an extremely high heat, meaning they will last you a very long time.