Why does sterling silver jewelry tarnish?

Sterling silver is comprised of 92.5% silver mixed with mainly copper. Sterling silver is somewhat soft, and is more prone to scratches, dents, and abrasions more than most karat gold and platinum alloys. Black dust causes sterling silver to tarnish by movement between the jewelry and the skin or clothing. People with moist skin, may find that sterling silver stains their skin green due to the copper component of the silver alloy. Soaps, detergent, home cleaning supplies, polish, chlorine and cosmetic creams may build up under a ring causing a type of dermatitis. Remove all rings before using any chemicals, soaps, or detergents. Also, keep silver jewelry out of swimming pools and hot tubs. Cleaning and polishing jewelry frequently can help to avoid discoloration of the silver and the skin.