A hallmark is an official stamp found on precious metal(s) that indicates the composition of the metal and its purity. Hallmarks may also include valuable information about the manufacturer and origin. As per BIS guidelines, a Hallmark consists of four compulsory steps. Recently the date letter has become optional while the rest remain compulsory as stated below. Precious metals are rarely used in its purest form and are usually alloyed with other metals for workability, durability, wearability. It is not possible to detect an article's precious metal content by sight or touch. Thus, it is a standard requirement for an Assaying & Hallmarking (A&HC) to hallmark articles containing precious metal(s) if they are described as such. Traditionally hallmarks are applied by striking with a punch. They are now also etched employing lasers.
This shows the fineness of the metal – that is purity of the precious metal content in parts per thousands in relation to the standard recognized in India. For example, 750 parts per thousand by weight is equivalent to the prior 18 carat gold standard. The alloy must be at least 750 parts per thousand to be marked as such. There is no negative tolerance.
Precious metals used in jewellery and giftware manufacture are always used as an alloy. The precious metal must be mixed with other elements to give it the necessary properties such as flexibility to produce a desirable and durable article. Even the most experienced jeweler or chemist cannot tell how much precious metal there is in an alloy by sight or similarly distinguish products that comprise of a thick plating of gold covering a base metal interior. Therefore, in the best interests of jewelers and consumers, all items being sold as gold (14, 18 or 22 carat) in India must be hallmarked to conform to the BIS standard. This cannot be done by the manufacturer or importer; articles must be submitted to one of the BIS certified Hallmarking Centers in India.
A BIS Standard of Hallmark includes these symbols:
Hallmarking is done on jewellery from jeweler partners based on hallmarking request as per BIS prescribed format. For retail individual customers, one must provide a declaration of the jewellery to be hallmarked as per prescribed format of MMTC-PAMP. Upon receiving work parcels, the Assaying & Hallmarking center will commence the hallmarking process which consists of following three steps:
1. 100% XRF (X-Ray Fluorescence Spectrometry) testing process, the Gold refining industry’s international standard, to precisely determine pure metal content.
2. Sampling, a traditional method to use a tiny piece of the precious metal for testing, after ensuring homogeneity.
3. Assaying to ensure the content of the precious metal meets the required standards.
4. Hallmarking, an appropriate mark with code of the jeweller, assaying certification mark, purity of Gold, and BIS logo.