Gold Alloys
American Watchmaker and Jeweler (1892)
Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
(See Alloys.) To Distinguish Genuine from Spurious Gold. Genuine gold dissolves in chlorine water and the solution has only a slightly yellowish color. Hence chlorine is a safe agent to distinguish genuine from spurious gold. To test the genuineness of gilt articles, rub a tiny drop of mercury on one corner of the surface to be examined; it will produce a white, silvery spot if the gold is pure, or if there is gold in the alloy. If this silvery spot does not appear there is no gold in the surface exposed. To prove the correctness of this result a drop of the solution of nitrate of mercury can be dropped on the surface, when a white spot will appear if the gold is counterfeit, while the surface will remain unaltered if the gold is genuine. After the operation, heating the article slightly will volatize the mercury and the spots will disappear. Pure gold can be distinguished from its alloys by a drop of chloride of gold or of nitrate of silver. If the gold is pure there will be no stain, but if mixed with other metals the chloride of gold will leave a brownish stain upon it and the nitrate of silver a gray stain. The simplest means of distinguishing genuine gold from a gold-like alloy consists in running the article to be tested against an ordinary flint until a lustrous metallic coloring remains upon the latter. Now hold a strongly sulphurated burning match against the coloring; if it disappears from the flint the article is not gold.
What Has Changed in the Last Century
The 1892 trade manual asked jewellers to identify gold by rubbing on mercury or striking sparks from a flint s real enough chemistry, but crude and, in the case of mercury, genuinely poisonous. Today the same shop counter test is done in seconds with a handheld X-ray fluorescence analyser, which reads the exact percentage of gold, silver, copper, palladium and nickel without touching or marking the piece; the acid-and-touchstone method survives as a cheap backup, while mercury testing has vanished from legitimate practice. The alloys themselves have also moved on: white gold, whitened with nickel or palladium, spread after the First World War as a substitute for scarce platinum, and legal hallmarking regimes now do much of the work that these home tests were meant to do. Nickel white gold has since been restricted in the European Union because of contact allergy, pushing the trade toward palladium-based whites.
Written for this edition, 2026.