How to Check Gold Purity: Hallmarks & HUID
You’re paying for a specific purity — but how do you know the gold in your hand is actually 22K and not something less? In India the answer is the BIS hallmark. Here’s how to read it and verify it before you buy.
Last updated: July 2026 · about a 5-minute read
What hallmarking is
Hallmarking is an official certification of a precious metal’s purity. In India it’s run by the Bureau of Indian Standards (BIS), and for most gold jewellery sold by registered jewellers it is mandatory. A genuine hallmark is your independent guarantee that the karatage stamped on a piece is what it really is — not just the seller’s word.
The marks to look for
A current BIS hallmark on gold jewellery has three components, usually stamped together in a small line:
- The BIS logo — a triangular mark. This is the assurance the piece was tested at a BIS-recognised Assaying & Hallmarking centre.
- The purity grade — a three-digit number showing fineness: 916 for 22K, 750 for 18K, 999 for 24K, 585 for 14K. (See our 22K vs 24K guide for what these mean.)
- The HUID — a six-character alphanumeric Hallmark Unique Identification code, unique to that individual piece.
The HUID — the piece’s fingerprint
The HUID is the most important recent change. Every hallmarked item gets its own six-character code, laser-engraved on the piece. Because it’s unique, it lets you (and the authorities) trace that exact item back to the jeweller and the hallmarking centre. It’s much harder to fake than a simple purity stamp, and it’s what makes modern Indian hallmarking trustworthy.
How to verify a hallmark before buying
- Look for all the marks. Ask the jeweller to show you the BIS logo, the purity number and the HUID on the piece — often near the clasp or on the inner surface. A magnifier helps; jewellers have one.
- Check the purity matches the quote. If you’re being sold “22K”, the number should read 916. A mismatch is a red flag.
- Verify the HUID. BIS provides an official “Verify HUID” feature in the BIS Care app. Entering the code should return the item’s registered details. If a code doesn’t verify, walk away.
- Get an itemised, stamped invoice. It should state the net gold weight, purity, and HUID. This protects you at resale.
Weight matters as much as purity
Two things determine your metal cost: how pure the gold is and how much it weighs. Insist the piece is weighed in front of you on a calibrated scale, and that the invoice shows the net gold weight — the gold alone, excluding any stones, beads or strings. For stone-studded jewellery, the stones should be weighed and priced separately, never charged at the gold rate.
At resale: purity protects you
When you sell or exchange gold, the buyer pays for verified gold content. A hallmarked piece with a matching HUID and invoice is faster to value and less likely to be discounted for “uncertainty”. Unhallmarked gold, or gold whose purity can’t be confirmed, typically fetches less. Keeping paperwork isn’t bureaucracy — it’s money.
Quick checklist for the shop
- ☐ BIS triangular logo present
- ☐ Purity number matches the karat quoted (916 = 22K, 750 = 18K, 999 = 24K)
- ☐ Six-character HUID present and verifiable in the BIS Care app
- ☐ Net gold weight confirmed on a calibrated scale
- ☐ Stones weighed and billed separately
- ☐ Itemised invoice with weight, purity and HUID