How Will Fake Gold React to an Acid Test?

Gold is so soft that when jewelry is made from it, it is usually alloyed with one or a combination of copper, nickel, and silver. If gold jewelry is immersed in an individual acid, the gold itself will not dissolve, although the alloying metal does dissolve. If a chunk of metal is fake gold--if it consists of a metal sample in which there is very little to no gold--it will dissolve in nitric acid.

Density First
Before treatment with acid, the density of the jewelry should be evaluated. Gold has a density of 19.3 grams per cubic centimeter of metal. Copper and nickel are less dense than that--8.96 and 8.91 respectively. Silver has a density of 10.49. If the density of the jewelry is not appreciably more than 9, the piece is fake. Even if it has a trace of gold in it, perhaps a plated covering, it is less than the 10-Karat designation of the lowest grade of solid gold jewelry.

Pure Gold
Pure gold, called also 24-Karat gold, dissolves in alkali cyanide and in a few other unusual substances. It will not, however, dissolve in individual mineral acids. It does dissolve in certain combination acids, most notably "aqua regia" (a mixture of concentrated hydrochloric and nitric acids). Gold dissolved in aqua regia produces a dark amber-to-orange color.

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