The 5 Causes of Gold Smudge
1) A person's skin secretions and perspiration may contain chlorides and sometimes sulphides. These chemicals combine with the molecules of silver and copper usually found in gold alloy to form dark-hued salts such as silver chloride and copper sulfate. Also, in some women, temporary changes in body chemistry during pregnancy may cause gold smudge.
2) Outside chemical influences may be to blame. In a maritime, semitropical climate (such as in southern Florida, for example) chlorides from the ocean may combine with normal skin secretions to form corrosive chemicals. In a factory work area, sulphides could be present . There's also the possibility that cosmetics or detergents may contain chemicals that may corrode a person's ring. (Handling salt or salty foods may contribute to this also)
3) Gold smudge may be due to simple tarnishing. Air and water may pollutants such as sulfur dioxide from the burning of low-grade coal or fuel oil or contain chemicals such as phosphates. These chemicals can attack gold alloys directly, even when Jewelry Isn't being worn. When an owner slips a ring on his finger or slides a bracelet on her wrist, the thin film of tarnish rubs off as a black smudge.
4) Black dermographism, a relatively rare occurrence, may also contribute to gold smudge. This condition,, literally "black writing on the skin," occurs when tiny particles of dust or powder become Imbedded In a person's skin. They result In a sort of "human sandpaper" that can wear away specks of karat gold from a ring, bracelet or necklace. These specks appear as an ugly black-violet smudge.
5) Allergies. This Is a rare condition, but gold and the metals used in alloys can cause an allergic reaction. Nickel is considered the worst offender. A dermatologist can identify which is the guilty metal.
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