A Chemical-Medical Mystery: Gold Jewelry and Black Marks on Skin

Abstract

Gold jewelry at times makes a black mark or smudge on skin. This may be caused by abrasive powders on the skin (e.g. zinc oxide) but the phenomenon may also be caused by other skin conditions, possibly the presence of chloride ion, acidity, or sulfur-containing amino acids. Some anecdotal evidence is published, but properly designed studies to clarify the actual causes are not available.

Black Dermographism

“…In late stages, there is often a hyperpigmented epidermis with dermal melanophages. 2 As previously reported, minocycline and doxycycline are often effective in PP, 3 as in our patients.…”

“…These metal particles are so small that they can absorb but cannot refract light, producing a jet black smear, no matter what the color of original bulk metal. This physical abrasion theory is proven by detection of metal particles by electron microscopy of the blackened skin . Black dermographism is easily demonstrated on anyone’s skin prepared with hard powder.…”

“…In 1929, Hauck conducted a study that found “true” black dermographism, in which the black smudge appeared without any previous preparation of the skin, occurred in 2.7% of those studied . For this subset of people, a chemical theory has been postulated that black dermographism is a reaction of metal with labile sulfur compounds in the sweat, and that sulfur-containing amino acid concentrations are hormonally controlled . This chemical reaction could potentially explain historic reports correlating black dermographism with the menstrual cycle .…”

“…4 For this subset of people, a chemical theory has been postulated that black dermographism is a reaction of metal with labile sulfur compounds in the sweat, and that sulfur-containing amino acid concentrations are hormonally controlled. 3,5 This chemical reaction could potentially explain historic reports correlating black dermographism with the menstrual cycle. 6 More scientific data need to be col- A, Rubbing her face with an 18-karat gold ring produces black smudges.…”

“…This physical abrasion theory is proven by detection of metal particles by electron microscopy of the blackened skin. 2,3 Black dermographism is easily demonstrated on anyone's skin prepared with hard powder. Normally, the black line remains until it is washed off with soap and water.…”