“Just look for the hallmark.” It’s the advice every careful relative gives before you buy gold, and it’s good advice as far as it goes. But a stamp is a small thing, and it’s worth understanding exactly what it promises — because a hallmark is only ever as honest as whoever pressed it into the metal.

What a hallmark is meant to do

A hallmark is a mark struck into a piece of gold or silver to certify its purity — that a “22K” piece really is 22K, and not quietly 20K wearing a 22K label. In systems with proper hallmarking, the metal is tested by an independent assay office, not just the seller, and the mark records the purity (often shown as a number like 916 for 22K, meaning 91.6% pure).

Done properly, this is genuinely valuable. It moves the question of purity from “trust this shopkeeper” to “trust an independent test,” which is a much stronger footing for the buyer.

Where the caution comes in

Here’s the honest part. A stamp is only meaningful if the body behind it is real and independent. A purity number punched in by the same person selling you the piece, with no third party involved, is a claim — not proof. And claims can be wrong, by mistake or on purpose.

A hallmark from an independent assay office is evidence. A purity number stamped by the seller alone is just the seller’s word, written in metal.

So the useful question isn’t only “is there a stamp?” but “who stands behind this stamp?” If a piece carries marks from a recognised, independent testing authority, that’s reassuring. If it carries only the shop’s own mark, treat the purity as something still to be verified.

How to actually verify purity

Beyond the stamp, you have practical options:

  • Ask for a machine test. Many reputable jewellers now have purity-testing machines that read the gold content without damaging the piece. Asking for this on an expensive purchase is completely normal.
  • Get it tested independently. For a large purchase, having the piece checked by someone who isn’t selling it removes all doubt.
  • Keep documentation. A proper invoice stating weight, karat and price is part of the protection. If a seller won’t put the karat in writing, that tells you something.

What hallmarking never covers

Even a perfect hallmark only certifies purity. It says nothing about whether you paid a fair making charge, whether the weight was read honestly, or whether the design is worth what you paid. Those are separate things you still have to check yourself — the weighing in front of you, the making charge as a clear number, the weight in writing.

The bottom line

Treat a hallmark as a helpful signal, not a guarantee. Favour pieces backed by independent testing, ask for a machine check on anything costly, get the karat and weight in writing, and remember the stamp says nothing about price. Combine that with knowing today’s rate before you walk in, and you’ve closed nearly every gap a careless buyer leaves open.