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The touchstone was used during the Harappa period of the Indus Valley civilization ca. 2600–1900 BC for testing the purity of soft metals. [2] It was also used in Ancient Greece. [3] The touchstone allowed anyone to easily and quickly determine the purity of a metal sample.
Apart from X-ray spectrometer technique, other older traditional methods are using the TouchStone and Acid to test the gold purity. But TouchStone and Acid are destructive testing - a tiny sample of gold is cut and then tested. The sample is rubbed on TouchStone and a drop of acid is put on it and the goldsmith observes the residue using a ...
In the past the assay was conducted by using the touchstone method but currently (most often) it is done using X-ray Fluorescence (XRF). XRF is used because this method is more exacting than the touchstone test. The most exact method of assay is known as fire assay or cupellation. This method is better suited for the assay of bullion and gold ...
Assay offices are institutions set up to assay (test the purity of) precious metals. This is often done to protect consumers from buying fake items. Upon successful completion of an assay (i.e. if the metallurgical content is found be equal or better than that claimed by the maker and it otherwise conforms to the prevailing law) the assay offices typically stamp a hallmark on the item to ...
XRF is used because this method is more exacting [clarify] than the touchstone test. The most exact method of assay is known as fire assay or cupellation. This method is better suited for the assay of bullion and gold stocks rather than works of art or jewelry because it is a completely destructive method.
The BIS system of hallmarking of gold jewellery began in April 2000. The standard specifications governing this system are IS 1417 (grades of gold and gold alloys, jewellery/artefacts), IS 1418 (assaying of gold in gold bullion, gold alloys and gold jewellery/artefacts), IS 2790 (guidelines for manufacture of 14, 18 and 22 carat gold alloys only ), IS 3095 (gold solders for use in manufacture ...
George Clooney had some pointed remarks about the Donald Trump administration, describing the current political climate as one where people “don’t worry about facts.” “You take a narrative ...
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.