BIS Hallmark Marks Explained: Purity, Logo and HUID

Turn over a gold ring or look at the back of a pendant and you will find a cluster of tiny marks. They are easy to ignore, but they carry the information that matters most about what you are buying. Here is how to read them.

The BIS logo

The Bureau of Indian Standards logo is a small triangle-like mark. It tells you the piece has been through BIS hallmarking. It is the first thing to look for. If a piece claims to be hallmarked but the logo is absent, ask why.

The purity mark

Next to the logo you will see a number that states purity. It is written in two ways at once: the karat and the fineness.

• 24K999 means 24 karat, 999 parts per thousand gold.
• 22K916 means 22 karat, 916 parts per thousand.
• 18K750 means 18 karat, 750 parts per thousand.
• 14K585 means 14 karat, 585 parts per thousand.

Fineness is the exact figure. For example, 750 means three quarters of the metal by weight is gold. A karat figure alone could be loosely quoted. The pair of numbers is much harder to fake by accident.

The HUID

The third mark is the Hallmark Unique Identification, a six-character code of letters and numbers. It is unique to the individual piece. We cover how to check it in what a HUID is and how to verify your jewellery.

Marks you may see on older jewellery

Before HUID, a hallmark usually had four parts: the BIS logo, the purity, the mark of the assaying and hallmarking centre and the jeweller's identification mark. If your family's jewellery has these, it was hallmarked under the earlier system. It is still a valid indication of purity for that piece.

Other stamps that are not hallmarks

Not every stamp inside a ring is a hallmark. You may also see a manufacturer's maker's mark, a size number or a brand name. These are fine, but they are not a replacement for the BIS marks. If all you see is a number such as "750" without a BIS logo or HUID, treat it as a claim, not a verified hallmark.

Where are the marks placed?

Hallmarks are applied by laser, in a spot where they will not spoil the design: the inner side of a ring or bangle, the clasp area of a chain, the back of a pendant or the post of an earring. On very small items the mark may be tiny. A jeweller can show it under a magnifier.

A quick checking routine

1. Look for the BIS logo.
2. Read the purity pair, for example 18K750, and compare it with the invoice.
3. Read the HUID and compare it with the invoice.
4. If you wish, enter the HUID in the BIS verification tool.

This takes under two minutes, and it is worth doing on a significant purchase. For the legal background, see whether hallmarking is mandatory for gold jewellery in India.

Why it protects you

A hallmark does not make a piece better looking. It does tell you that purity was tested by someone with no interest in the sale. That matters when you buy, when you exchange old gold and when you pass jewellery to the next generation. If you would like to be shown a hallmark on a real piece, book a visit to our Patna showroom, or browse necklaces and read the listed purity on each product page.