Your customers may think that faulty manufacturing or underkarating might be the problem when a ring "turns," blackening or discoloring the skin and clothing, or the jewelry itself. However, that is not the case. You can help them understand the causes, and how to prevent them.

The most common reason is metallic abrasion, caused 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 sticks, forming a black smudge.

To prevent this, your customers should try switching cosmetics. If this is not possible, recommend that they remove rings and other jewelry while applying them, and clean skin 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 combine 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 points that trap moisture and contaminants, also causing a type of dermatitis.

Have customers remove all rings before using soaps, 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 actions, recommend that customers switch to 18-karat gold or platinum. The lower alloy content of 18-karat gold (25%, versus almost 42%) significantly reduces the problem, and the use of platinum should eliminate it completely.