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The BIS Hallmark is a hallmarking system for gold as well as silver jewellery sold in India, certifying the purity of the metal. [1] [2] It certifies that the piece of jewellery conforms to a set of standards laid by the Bureau of Indian Standards, the national standards organization of India.
A hallmark is an official mark or series of marks struck on items made of metal, mostly to certify the content of noble metals—such as platinum, gold, silver and in some nations, palladium. In a more general sense, the term hallmark is used to refer to any standard of quality. Not to be confused with responsibility marks that are the marks of ...
For example, knowing that standard 18-carat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by mass), the volume of pure gold in this alloy will be 60% since gold is much denser than the other metals used: 19.32 g/cm 3 for gold, 10.49 g/cm 3 for silver and 8.96 g/cm 3 for copper.
If the gold layer is 12 kt or higher, the minimum layer of karat gold in an item stamped gold-filled marks must equal at least 1 ⁄ 20th the total weight of the item. The most common stamps found on gold-filled jewelry are 1 ⁄ 20th 12kt GF and 1 ⁄ 20th 14kt GF. Also common is 1 ⁄ 10th 10kt. These standards are for modern gold-filled items.
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 ...
French ormolu mantel clock (around 1800) by Julien Béliard (1758 – died after 1806), Paris.The clock case by Claude Galle (1758–1815) Ormolu (/ ˈ ɔːr m ə ˌ l uː /; from French or moulu 'ground/pounded gold') is the gilding technique of applying finely ground, high-carat gold–mercury amalgam to an object of bronze, and objects finished in this way.
Rose gold jewelry is becoming more popular in the 21st century, and is commonly used for wedding rings, bracelets, and other jewelry. Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content: the higher the copper content, the stronger the red coloration.
Speidel experienced a boom in popularity, notably with their invention of the hugely popular expanding strap in the mid-1930s, and in addition to watchbands Speidel produced wristwatches, lighters, writing instruments, small jewelry, and other accessories, before beginning to decline by the end of the century with the struggle to compete with ...