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The Karatmeter is a scientific instrument which uses X-rays to give an exact reading of the purity of gold. The Karatmeter is also referred to as a X-Ray fluorescence (XRF) spectrometer. Due to its very high precision and fast result, X-ray analysis has been adopted by international agencies in India as part of the certification process used to ...
An acid test is a qualitative chemical or metallurgical assay utilizing acid. Historically, it often involved the use of a robust acid to distinguish gold from base metals . Figuratively, the term represents any definitive test for attributes, such as gauging a person's character or evaluating a product's performance.
A model of a late 19th-century Canadian seal used to certify the quality of assayed gold. A metallurgical assay is a compositional analysis of an ore, metal, or alloy, usually performed in order to test for purity or quality. Some assay methods are suitable for raw materials; others are more appropriate for finished goods.
This method has been used since ancient times. In modern times, additional tests can be done. The trace will react in different ways to specific concentrations of nitric acid or aqua regia, thereby identifying the quality of the gold: 24 karat gold is not affected but 14 karat gold will show chemical activity.
For example, a gold alloy of 127 ⁄ 128 fineness (that is, 99.2% purity) could have been described as being 23-karat, 3-grain, 1-quart gold. The carat fractional system is increasingly being complemented or superseded by the millesimal system, described above for bullion, though jewelry generally tends to still use the carat system.
The rationale for biting a coin was the supposed widespread dissemination of gold-plated lead coins in the 19th century. Since lead is much softer than gold, biting the coins is a sensible test for counterfeiting. While fine gold is softer than alloyed gold, and galvanized lead is softer, biting coins can only detect the crudest of forgeries.
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When used as a test, the intensity of the color correlates with the concentration of gold present. This test was first observed and refined by a German physician and alchemist, Andreas Cassius (1600–1676) of Hamburg, in 1665. Berzelius later made a detailed study of the purple of Cassius. The colour also attracted attention from Faraday. [1]