Why Gold Discolors
The most common reason for jewelry “turning,” or discoloring is metallic abrasion, caused by makeup. Cosmetics often contain compounds which wear or rub off very tiny particles of the precious metals. 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 try switching cosmetics. If this is not possible, remove rings and other jewelry while applying makeup, and then clean the skin areas in contact with the jewelry with soap and water.
Another cause of discoloration is the actual corrosion of the metals. Gold itself does not corrode, or oxidize, but its alloy materials of silver and copper will do so forming very dark chemical compounds under moist or wet conditions.
When you perspire, fatty acids released in the perspiration can cause corrosion of 14 karat (or less) gold, especially when exposed to warmth and air. This problem can be worse in seacoast and semitropical areas, where chlorides combine with the perspiration to form a corrosive element that discolors skin. Even smog fumes will gradually attack jewelry, and is evident as a tarnish that rubs off on the skin.
Under these conditions, you should remove your jewelry often, and use an absorbent powder, free of abrasive compounds, on skin that comes in contact with jewelry.
Sometimes, the actual design of the jewelry can become an influencing factor. Wide shanks have more surface area to contact abrasives or corrosives. Concave surfaces inside a shank form natural collection points that trap moisture and contaminants, also causing a type of dermatitis.
You should remove all rings before using soaps, cleaning compounds, or detergents, and clean your rings frequently. Besides solving the discoloration problem, you will be amazed at how much better your rings look!
In addition to these corrective measures, you might want to switch to 18 karat gold or platinum jewelry. The lower alloy metal content of 18 karat gold (25 percent versus almost 42 percent), significantly reduces the problem, and the use of platinum should eliminate it completely.