What the Stamps Inside a Ring Mean

The marks sit inside the shank, usually opposite the stone, and on a signet ring often under the face. They are shallow, they are small, and forty years of skin oil turns a crisp punch into a smudge. Clean the inside of the band, then photograph it with a phone camera zoomed fully in and read the marks on the screen rather than through a loupe held at arm's length.

Expect two kinds of mark. One is a number describing the metal. The others are symbols and initials describing who is responsible for the piece, where it was tested and, sometimes, in which year. The number is the one that decides what the ring is made of.

Fineness is quoted as parts of precious metal in every thousand parts of alloy. 750 means seventy-five per cent gold, which is eighteen carat. Carat is the same fact expressed in twenty-fourths, so eighteen carat is eighteen parts gold in twenty-four. Once that clicks, the whole set of numbers stops needing memorising.

Higher is not automatically better for a ring that will be worn. Twenty-two and twenty-four carat gold are soft enough to bend out of round; eighteen is the luxury standard; fourteen is harder and more practical; nine carat, common in Britain, contains more copper than gold and is tougher again.

A number on its own describes solid metal all the way through. A number with letters attached usually describes a coating. GP and GEP are gold plated: an electroplated skin measured in microns, worth nothing as metal and destined to wear through at the base of the band. HGE means heavy gold electroplate, which is still plating. RGP is rolled gold plate.

GF, gold filled, is the honourable member of this family. A sheet of karat gold is mechanically bonded to a brass core, and United States rules require the gold to be at least five per cent of the total weight — which is why the mark often reads 1/20 12K GF. It survives decades of wear and is still not solid gold, and a jeweller will decline to resize it.

This is the single most common confusion we are asked about. A warm yellow ring stamped 925 is not gold. It is sterling silver with a gold layer over it, generally sold as vermeil, and it is a legitimate product — real silver underneath, a heavier gold layer than ordinary plating on top. It is priced on the silver, and the plating will eventually wear at the points that rub.

Related marks worth knowing: KP after a karat number means karat plumb, a claim that the piece assays at exactly the stated fineness rather than inside the small tolerance the law allows. SS almost always means stainless steel. Nickel silver, German silver and alpacca contain no silver whatsoever.

Two or three letters in a shaped shield are a sponsor's or maker's mark, identifying who submitted the piece rather than necessarily who made it. A town symbol identifies the assay office that tested it: in Britain, a leopard's head for London, an anchor for Birmingham, a rose for Sheffield, a castle for Edinburgh. A single letter in its own shield is a date letter, and it can pin the year exactly.

In the United Kingdom the sponsor's mark, the fineness mark and the assay office mark are the compulsory three; the traditional pictorial marks and the date letter are voluntary additions. Elsewhere, symbols carry the fineness instead of numbers — an eagle's head for eighteen carat gold in France, a clover for nine, Minerva's head for sterling silver, a dog's head for platinum.

An unmarked ring is an open question rather than a bad sign. Resizing cuts out a section of the shank and takes the marks with it. Decades of polishing wear a shallow punch flat. Plenty of good gold was made in places and periods that never required marking at all, and in the United States marking only became a legal matter in 1906.

In that case the sequence is: a magnet, which precious metals ignore and a steel core does not; the weight in the hand, because platinum in particular feels wrong-heavy for its size; and then an X-ray fluorescence reading at a jeweller or a gold buyer, which names the alloy in seconds without touching the surface. Acid testing works too and leaves a small scratch, which is fine for scrap and wrong for anything you intend to keep.

It says nothing about the stones. A ring stamped 750 can hold a fine diamond, a treated sapphire or a cubic zirconia, and the metal mark is identical in all three cases. It says nothing about who made the ring well, and nothing about age beyond what a date letter offers. It is a statement about alloy, and only that.

It also says nothing about value, because value follows weight, stones, brand and condition. Read the stamp first because it is the fastest and most reliable fact available, then weigh the ring, then deal with the stones — in that order, because each answer narrows the next question.