Why is gold white, black, rust, faded

Gold, known as gold, its chemical element symbol for Au, is a metal with yellow luster. Gold has good physical properties, stable chemical properties, high ductility and the characteristics of scarcity, the chemical and physical properties is very stable. But! Why is gold white, black, rust, fade, this is really the quality problem? Why gold white? Gold has good physical properties, stable chemical property, high ductility and the characteristics of scarcity, it is generally thought that the nature of the gold is stable, but now people contact of cosmetics, daily skin care products is increasing, some varieties of makeup contains trace mercury, the use of cosmetics, if touch gold jewelry, here will become white, 'as the mercury containing gold. Also, if someone in the same wearing a gold ring on a finger of the hand, and the adjacent finger a platinum ring, due to the need to move finger, easy to cause the mutual friction, gold and platinum ring ring to make gold jewelry surface on local ceng platinum hair white. This heating gasoline spray wheel can not be used to make it disappear, because the melting point of platinum is higher than the melting point of gold for baidu, when melting gold platinum also 'place'. For such variable white gold jewelry, can use agate knife plane light, also can use the coarse cloth ( Such as canvas) Rub, namely can make gold recovery back should be light. Why will turn black gold? Some containing trace amounts of lead in cosmetics or hair dye, black gold met lead easily. For the above two has white black gold jewelry, can use gasoline spray wheel with jewelry processing heat treatment, because the melting point of mercury and lead is very low, in spraying rounds heating processing, can volatilize, restore true colors to gold jewelry. , of course, had better wipe in cosmetics or hair color do not wear gold jewelry, to avoid future trouble. Gold jewelry color or fade with the body's sweat has a close relationship. People sweat is 99% water, the other 1% is the body of waste and harmful substances, such as chlorinated, lactic acid, urea, ammonia, etc. These substances with gold jewelry in silver and copper after contact, can produce chemical reaction, the silver chloride and copper sulfide, and render the deep black chemical salts. These chemical salt often fall off from the gold jewelry, pollution of the wearer's skin, evident in the skin of black stains. Jewelry worn parts of the skin, and will give cosmetics containing chemical substances and the most afraid of chemical erosion gold jewelry 'last elected' opportunity, causing discoloration. Some cosmetics, but also includes some subtle grain, it can constitute another type of dirt, to wear gold jewelry. Such as gold and silver ornaments worn by health care workers is the most easily because of the environment and produce discoloration. Once appear fade the above situation, consumers can to the jewelry store to high temperature fire processing of gold, pure gold if it is, should be able to restore color. Gold why rust? Why in the jewelry store to buy gold jewelry, gold bars, gold COINS appeared yellow-brown spots? Because in the process of jewelry making, iron processing tools of scrap iron left in moisture, not quality problem, clean can. Why gold fading? Some cosmetics, but also includes some subtle grain, it can constitute another type of dirt, so as to wear gold jewelry. Regional environmental factors may also lose gold jewelry bright beautiful colour and lustre. Such as: the dry region, contains more fine dust in the air, after pick up the human body can form a kind of 'human sandpaper, it can put the gold jewelry abrasive wear out very fine clastic, a local black stains, etc. It is worth mentioning that the talcum powder or lotion also contain similar particles, also like the shine off gold jewelry.