How Come Gold Jewelry Turns White Sometimes?
Sometimes customers come to me and ask why their gold jewelry suddenly changes color or has white spots, worrying about that they may have bought a fake.
In fact, usually these worries are unnecessary. Under normal circumstances, as long as it is bought from a regular gold shop, the quality of the gold jewelry is guaranteed. After a little jewelry cleaning by some staff in a gold shop, the white spots on the gold will disappear, and the jewelry will be re-lit as new.
Why would this happen? How come the gold jewelry turns white? Gold is one of the nature's most stable metals, and it does not react with any oxide gas in the air at room temperature, nor with three major acid (sulfuric acid, nitric acid, hydrochloric acid) or weak acid. Only aqua regia (a mixture of hydrochloric and nitric acid) can corrode it. But mercury is an exception, it is very easy to react with gold and produce a white compound called amalgam. Therefore, once the gold jewelry is exposed to mercury, it will turn white immediately. And because mercury is volatile, it can cause discoloration of gold even from a distance.
This may occur in the home, because mercury or mercury-type substances exist in many detergents, cosmetics and skin care products. If gold is exposed to these items, it is likely to change its color, turning white, gray, or dark. Many ladies have a habit of using skin care product before touching their jewelry, which makes the chemicals contact the gold directly and causes discoloration of the jewelry. In addition, perfume, hair spray, sea water, swimming pool water, and dirt caused by long-term wearing, are also likely to make gold jewelry change its color or fade. This has nothing to do with the purity of the gold, and it does not mean the jewelry is a fake.
Gold jewelry should be kept from direct exposure to the substances referred, and should be cleaned regularly. And if the surface of gold jewelry has changed color, do not use a hard object or tool to eradicate the changed part. The correct approach is to use alcohol lamp or welding torch which is used in jewelry processing to heat the white part of the gold, so that mercury can sublimate out of amalgam and separate from gold. When the jewelry gets cool, brush it lightly with a toothbrush, and then wipe it and press it hard for a few times with a soft cloth, after which the gold will recover its color. But do not try to do this with a lighter, because the jewelry will turn black easily for incomplete combustion of the gas. K gold and inlaid jewelry do not suit this method, they should be taken to the gold shop to have other proper treatment. However, if consumers do have doubts about the quality of their jewelry, they should go to the professional department and have the jewelry identified as soon as possible.