Gold Hallmark Identification Chart: Every Stamp, What It Guarantees, What It's Worth

How to use this chart in thirty seconds

Find the stamp on the piece — inside a ring band, on the clasp tongue or the small flat tag beside it, on a pendant bail, inside a watch caseback, on an earring post. Use a 10× loupe and light from the side; phone cameras blur the strike. Then match what you see to one of the eight rows in the chart.

The right-hand column is the one that matters for money. Full value means the whole piece is gold alloy of the stated purity — weigh it, multiply, and you have the melt value. A share of weight means a real gold layer over base metal, worth a few percent of what the scale implies. Near zero and not gold mean the metal value is in something other than gold, or in nothing at all. The sections below take each row in turn, with the marks you will actually meet and the ones that trip people up.

What do American karat marks guarantee?

A karat is one twenty-fourth. The stamp asserts the minimum fineness of the alloy throughout the piece; there is no separate layer to worry about. Two suffixes change nothing about the gold content but tell you something about the maker: KT is simply an older abbreviation, and KP — "karat plumb" — is a maker's promise that the alloy is exactly the stated karat with no negative tolerance, a distinction that mattered more before US stamping rules tightened the allowed tolerance.

What a bare karat mark does not do is prove anything. It is a manufacturer's claim, and US law requires a registered trademark beside it precisely so that someone is accountable for the claim; a karat stamp with no maker's mark next to it is legal only in narrow cases and is worth testing. The gold hallmarks guide covers where the marks hide and what a missing trademark means; the gold purity chart has the same karat table with per-gram values.

Millesimal fineness — parts per thousand

Most of the world stamps purity in thousandths rather than twenty-fourths, and the two systems are just different units for the same number: 750 is 18K, 585 is 14K, 916 is 22K. The conversion is karat ÷ 24 × 1000.

Two details separate a confident reading from a guess. First, 583 and 585 are both 14K — Soviet and Eastern-bloc makers used 583 for decades, and the site's karat constants treat them as equivalent. Second, a three-digit number on its own is not always a fineness mark: 925 is sterling silver, 950 with PT or PLAT is platinum, and a four-digit number on a watch is usually a model reference. The gold fineness chart plots every mark on one scale if you want to see how uneven the steps really are.

Why is a UK hallmark the only mark you can trust without testing?

British hallmarks are different in kind from every other row on this chart. A karat stamp is the maker's claim; a UK hallmark is an assay office's certification that it tested the metal, applied under the Hallmarking Act 1973 by one of the four UK assay offices. That is why a genuine UK-hallmarked piece is the one you can weigh and value without a second thought.

The compulsory set has three parts, struck as a group:

1. Sponsor's mark — the maker's or importer's initials in a shield or cartouche.
2. Millesimal fineness — for gold, one of 375, 585, 750, 916, 990 or 999, inside an octagon-shaped surround that itself signals "gold" (silver and platinum use different shapes).
3. Assay office mark — a leopard's head for London, an anchor for Birmingham, a rose for Sheffield, a castle for Edinburgh.

Two further marks are optional since 1999 and common on older pieces: a date letter that specialists use to year the piece, and the traditional crown that historically denoted gold. A piece with only some of the set is either pre-1999, foreign-made with a partial import mark, or not hallmarked at all — and the last case means it is a claim again, not a certification.

For valuation the practical rule is simple: read the fineness number from the octagon and treat it as exact. The how much is 18K gold worth page runs the numbers for the 750 mark that dominates UK fine jewelry; 375 pieces use the 9K row of any karat calculator.

India's BIS hallmark — logo, grade, HUID

Indian gold carries the Bureau of Indian Standards hallmark, which under the mandatory regime in force since 2021 has three components struck together:

• The BIS logo — a triangle mark.
• The purity and fineness grade — written as both, for example 22K916, 18K750, 14K585.
• A six-digit alphanumeric HUID (Hallmark Unique Identification) that is specific to the individual piece and can be checked against the BIS database.

The grade is what the calculator needs: 22K916 is 91.67% gold, exactly as a Western 916 or 22K mark would be. The HUID is what makes the Indian system closer to the UK's than to the American one — a piece with a valid HUID has passed through an assay and hallmarking centre rather than being self-stamped by the maker. Older Indian pieces may carry the earlier BIS format with a jeweller's identification mark and an assay-centre mark in place of the HUID; the fineness number is read the same way.

Most of the Indian gold that reaches Western counters is 22K, heavy, and sold by weight in its home market, which makes it the single easiest category on this chart to value: weight × 0.9167 × the price of pure gold. The 22K gold calculator is preset for it.

Gold filled and rolled gold plate — the fraction changes everything

Any stamp with a fraction in front of the karat is describing a layer, not the whole piece. The fraction is the layer's share of the metal weight; the karat is the layer's purity; multiply them for the piece's real gold content.

The FTC's rules fix the thresholds. "Gold filled" (GF, G.F.) may only be used when a mechanically bonded layer of at least 10-karat gold makes up at least one-twentieth of the metal weight. Below that, down to one-fortieth, the same construction must be called "rolled gold plate" (RGP, R.G.P.) or "gold overlay," with the fraction shown. A bare GF with no fraction still has to meet the 1/20 minimum, so read it as 1/20 at 10K — about 2% fine gold — for a conservative estimate.

These pieces are real gold in small quantity. They are worth decoding precisely, and the 1/20 12K GF page does the full decode for the commonest stamp; the gold filled calculator turns any of them into a dollar figure. What they are not is jewelry-counter scrap: a pawn shop or jeweler cannot recover 2.5% gold from brass and will decline or offer a token amount. Refiners with a published gold-filled rate are the outlet, usually above a minimum lot weight.

Which stamps mean almost nothing?

The bottom two rows of the chart are where most expensive mistakes happen, because the pieces look identical to solid gold and the stamps sound reassuring.

GEP, GP, gold electroplate. An electrolytic gold film measured in microns of thickness rather than in a weight fraction. The FTC minimum for the plain term is 0.175 microns; for HGE (heavy gold electroplate) it is 2.5 microns. Even the heavy grade amounts to a negligible share of the piece's weight — a hundredth of a percent or less — so the recoverable gold rounds to zero and no buyer pays for it. Marks like "18K GEP" or "14K HGE" are describing the purity of a film you cannot sell.

Vermeil. Gold over sterling silver, at least 10-karat and at least 2.5 microns thick by the FTC definition. The gold layer is worth nothing recoverable; the silver base is worth silver melt. Look for 925 beside the gold mark.

"18K gold-tone," "gold color," "gold finish." Not gold in any regulated sense. Costume.

925, Sterling, PT950, PLAT, Stainless, Titanium. Not gold at all — silver, platinum or steel marks. A piece stamped 925 with a gold appearance is vermeil or gold-plated silver, and the gold plated jewelry value guide explains why even a refiner will only pay for the silver.

The common thread: a karat number next to a layer term (GEP, HGE, GP, vermeil, gold-tone) describes the layer, never the piece. When in doubt, the how to tell real gold from fake tests separate a plated piece from a solid one in a minute, and a buyer will run them whether you do or not.

Maker's marks, country marks and the stamps that aren't purity at all

A great deal of what is struck on jewelry has nothing to do with gold content, and reading it as if it did causes confusion in both directions.

When a piece carries several marks, the rule is to find the purity mark first — a karat, a millesimal number in the right surround, a BIS grade — and treat everything else as context. The gold basics guides cover each of these systems in more depth; the gold percentage to karat chart is the reverse lookup for when a piece shows a percentage rather than a mark. And the last step is always the same: weight × purity × the live price, which the karat gold calculator does for any mark on this page.

Frequently Asked Questions