A hallmark is an official mark certifying the purity of a precious metal article. In India the scheme is run by the Bureau of Indian Standards, and the marks are applied at a BIS-recognised Assaying and Hallmarking Centre after the metal has been tested — not by the jeweller selling it. That independence is the entire point.
The three marks
Since July 2021 a BIS hallmark on gold jewellery consists of three marks: the triangular BIS standard mark, the purity and fineness together (22K916, 18K750 or 14K585), and a six-digit alphanumeric Hallmarking Unique Identification number — the HUID — which is unique to your individual piece.
Hallmarks applied before that change carried four marks, including the jeweller's own mark and the assaying centre's mark. Older four-mark jewellery is still validly hallmarked.
What the number means
The three-digit figure is fineness: parts of pure gold per thousand. 916 is 91.6% pure, which is 22 karat. 750 is 18 karat and 585 is 14 karat.
Higher is not automatically better. 22K is richer in colour but softer, and a 22K claw will bend where an 18K one holds. That is why fine gemstone jewellery is usually made in 18K or 14K.
Where to look
The marks are struck small and placed where they will not show when the piece is worn — inside a ring shank, on a clasp, on the reverse of a pendant. A jeweller's loupe or a phone camera at full zoom will make them legible.
Checking it
Enter the HUID in the official BIS CARE app published by the Bureau of Indian Standards. The purity it returns should match what you were sold and what your invoice says.
Hallmarking of silver remains voluntary in India, so an unmarked silver piece is not irregular.
