Reading Gold Hallmarks — What 916, 750 and 585 Actually Tell You

A hallmark is a small stamp, usually on the inside of a ring or the clasp of a chain, and it is the only part of a gold purchase that does not depend on trusting the person selling it to you. Everything else — the quoted karat, the weight, the making charge — is a claim. A hallmark from a recognised assay office is a third party's certification.

The number is the purity

The core mark is a three-digit number: parts of gold per thousand.

Once you know that, most of the mystery disappears. A "916" chain is 22 karat. A "750" ring is 18 karat. Some pieces carry the karat directly instead — "22K", "18K", "14K" — which is common in the United States and the Gulf.

What a full hallmark contains

Different countries certify differently, but a complete hallmark usually carries three or four elements:

• The purity number — as above
• The assay office mark — which office tested and certified it
• A jeweller or maker's mark — who made it
• Sometimes a year or batch code

India — BIS

India's Bureau of Indian Standards runs a mandatory hallmarking system for gold jewellery. A current BIS hallmark carries:

• The BIS logo
• The purity in both karat and parts per thousand (for example "22K916")
• A six-character alphanumeric HUID — a unique identification number for that specific article

The HUID is the useful part: it identifies the individual piece, not just its grade, and can be checked through BIS's own verification channels.

United Kingdom

UK hallmarking is among the oldest continuously operating systems in the world and remains compulsory above small weight thresholds. A UK hallmark shows a sponsor's mark, a fineness number, and an assay office symbol — a leopard's head for London, an anchor for Birmingham, a rose for Sheffield, a castle for Edinburgh.

The Gulf

The UAE, Saudi Arabia and neighbouring markets operate their own hallmarking regimes, generally requiring purity marking on jewellery sold at retail. In Dubai, the enforcement regime around gold retail is a large part of why the market has the reputation it does.

Testing when there is no hallmark

An unstamped piece has an unverified purity. That does not automatically mean it is fake — older and inherited pieces frequently predate mandatory hallmarking — but it does mean nobody can tell you its karat by looking.

Ways it can actually be established, from least to most reliable:

The magnet test. Gold is not magnetic. If a piece is attracted to a strong magnet, it contains a substantial magnetic metal and is not solid gold. Passing this test proves very little, though — many non-gold metals are also non-magnetic.

Density. Pure gold is 19.32 g/cm³, which is far denser than almost anything used to imitate it. Weighing a piece and measuring its water displacement gives a density that rules out most fakes. Tungsten is the notable exception, being very close to gold in density — which is exactly why it appears in counterfeit bars.

Acid testing. A jeweller applies graded acids to a scratch of the metal; the karat is inferred from which acid dissolves it. It is destructive in a small way and tests only the surface, so it can be defeated by heavy plating over base metal.

XRF analysis. An X-ray fluorescence gun reads the elemental composition without damaging the piece. This is what serious buyers use. It reads the surface layers, so a thick plating can still mislead it, which is why valuable items are sometimes tested at a drilled point.

Assay. Destructive, definitive, and reserved for bulk or high-value lots.

Practical advice

• Buy hallmarked. The premium over unstamped work is small relative to what you are protected from.
• Check the mark before you pay, not after. Ask for a loupe; any real jeweller has one.
• In India, ask for the HUID and confirm the invoice matches it.
• Keep the invoice. It should record weight, purity, making charges and the hallmark. That document is what you will need when selling or insuring.
• Be sceptical of large discounts on unstamped gold. The saving is usually smaller than the risk.

Once you know the purity and weight, you can compute exactly what the metal in a piece is worth with our karat calculator.