Why does white gold turn yellow? A customer who bought a very expensive 18-karat white gold and diamond ring last year is now complaining that the mounting is looking dingy and yellowish. What could be the problem? Or is she just imagining things? The customer is definitely not imagining things. Most white gold rings are flash plated with a very, very thin coating of rhodium (a pure white metal) to give them a more brilliant, pure white appearance. This rhodium plating will wear off over time and reveal the "real" white gold ring underneath. Because pure gold is very yellow, no matter how much you alloy it with other metals like zinc and nickel, it will almost always retain some of its yellowish body color. The solution to your customer's problem is quite simple. Most bench jewelers can easily re-plate a white gold ring with rhodium for very little cost. Also, many manufacturers will re-plate the rings they sell. Check with both your bench jeweler and the company that made your customer's ring to decide on the best course of action. On final thought: if a customer want a truly white metal that won't require any future re-plating, steer them toward platinum. It is naturally pure white in color. Why Does Gold Discolor Fingers? Your customer may think that faulty manufacturing or under-karating might be the problem when a ring "turns," blackening or discoloring the skin and clothing, or the jewelry itself. The most common reason is metallic abrasion, cause by makeup on skin or clothing. Cosmetics often contain compounds harder than the jewelry itself, which wear or rub off very tiny particles. Very finely divided metal always appears black rather than metallic, so it looks like a jet-black dust. when this dust comes into contact with absorbent surfaces such as skin or clothing, it stick, forming a black smudge. To Prevent this, your customers should try switching cosmetics. If this is not possible, recommend that they removed rings and other jewelry while applying them, and clean shin areas in contact with jewelry with soap and water. Another cause is actual corrosion of the metals. Gold itself does not corrode, but its primary alloys of silver or copper will do so -- forming very dark chemical compounds -- under moist or wet conditions. When your customer perspires, fats and fatty acids released can cause corrosion of 14-karat gold, especially when exposed to warmth and air. This problem can be worse in seacoast and semitropical areas, where chlorides combining with perspiration to form a corrosive element that discolors skin. Smog fumes gradually attack jewelry and are evident as a tarnish that rubs off on the skin. Suggest that your customer remove jewelry often and use an absorbent powder, free of abrasives, on skin that comes into contact with jewelry. Even the design of jewelry can be an influence. Wide shanks have more surface area to contact abrasives or corrosives. Concave surfaces inside a shank form collection point that trap moisture and contaminants, also causing a type of dermatitis. Have customer remove all rings before using soap, cleaning compounds or detergents, and clean their rings frequently. As well as solving the problem, they'll be amazed at how much better their rings look! In addition to these corrective action, recommend that customers switch to 18-karat gold or platinum. The lower alloy content of 18-karat gold -- 15%, versus almost 42% -- significantly reduces the problem, and the use of platinum should eliminate it completely.