How to Check Gold Purity Before You Buy: Hallmarking and Karat Marks Explained

You can't tell gold purity by looking at it or biting it, despite what folklore suggests. In India, the reliable way to verify purity is the BIS hallmark — an independent certification, not a claim the jeweller is making about their own product.

What a BIS hallmark actually certifies

The Bureau of Indian Standards (BIS) runs India's hallmarking scheme for gold jewellery and artefacts. A hallmarked piece carries a BIS mark, a purity/fineness grade, and a HUID — a unique alphanumeric code assigned to that specific piece, traceable back to the assaying centre that certified it. That traceability is the point: it's much harder to fake a HUID-linked hallmark than to print a purity number on a price tag.

Reading the purity grade

Purity is stamped as a number, not directly as "24K" — the number is the fineness out of 1000:

• 999 — 24K, 99.9% pure. Too soft for most jewellery; mainly coins and bars.
• 916 — 22K, 91.6% pure. The most common purity for traditional Indian jewellery.
• 750 — 18K, 75% pure. Common in diamond and gemstone-studded jewellery, where the alloy adds strength to hold stones.
• 585/583 — 14K, about 58.5% pure. Less common in India, more common in Western-style jewellery.

What to actually check at the counter

• Look for the BIS triangle mark and the fineness number stamped on the piece itself, not just printed on the tag or box.
• Ask for the HUID and, if you want to verify it, check it through BIS's own verification channel rather than taking the jeweller's word for it.
• Match the stamped purity against what you're being billed for — if you're paying a 22K price, the stamp should read 916, not 750.
• Get the purity written on your invoice, not just stated verbally. It's your evidence if there's ever a dispute.

Why this matters beyond honesty

Purity isn't just an ethical question — it's the single biggest input into what the gold in your jewellery is actually worth. A 22K piece and an 18K piece of the same weight are genuinely worth different amounts, because 91.6% pure gold and 75% pure gold are different amounts of actual gold. Confirming the hallmark before you buy is what makes every other number on your bill — the gold value calculation, resale value, exchange value — trustworthy.