Jewelry stamps and markings: a chart for gold, silver and platinum

How to read a jewelry stamp

Most jewelry stamps answer one of three questions: what the metal is, how pure it is, and who made or tested it. A purity mark (also called a quality or fineness mark) states the metal content, either in karats, such as 14K, or as parts per thousand, such as 585. A plating mark tells you that only the surface is precious metal. A maker's mark or trademark names the company that stands behind the quality mark, and in some countries an assay office adds its own hallmark after testing the piece.

Use a 10x loupe and bright, angled light, and read each mark exactly as it appears, including letters next to the numbers. A number on its own can mean different things for different metals, so the letters and the color of the piece matter. The charts below cover the marks you will see most often; for anything unusual, look it up rather than guessing.

Gold marks: karats and fineness numbers

Gold purity is shown either in karats, out of 24, or as a three-digit fineness number in parts per thousand. Both describe the same thing: the share of pure gold in the alloy. These are the standards you are most likely to meet:

• 9K = 375: 37.5% gold, common in the UK and Ireland.
• 10K = 417: 41.7% gold, the lowest karat that can be sold as gold in the US.
• 14K = 585: 58.5% gold, very common in the US and much of Europe.
• 18K = 750: 75% gold, standard for fine jewelry in much of Europe.
• 22K = 916 or 917: about 91.6% gold, popular in South Asia and the Middle East.
• 24K = 999 or 999.9: essentially pure gold, more common in bullion than in jewelry.

Plating and gold filled marks

Some of the most important marks on a piece are the ones that say the gold is only on the surface. US jewelry guides set out how these products must be described, and they are worth learning because they often appear right next to a karat number:

• GP or GEP: gold plated or gold electroplated, a thin layer of gold over a base metal.
• HGE or HGP: heavy gold electroplate, a thicker plated layer, still only on the surface.
• GF or a fraction such as 1/20 12K GF: gold filled, a layer of karat gold bonded to a base metal that makes up at least one twentieth of the weight.
• RGP: rolled gold plate, the same idea as gold filled but with a thinner gold layer.
• Vermeil: sterling silver with a coating of karat gold of a specified minimum fineness and thickness.
• EP or EPNS: electroplated, often electroplated nickel silver, an alloy that despite its name contains no silver.

Silver marks

Silver marks follow the same parts-per-thousand logic. In the US, sterling must be at least 925 parts per thousand silver, and coin silver at least 900. The unqualified word silver should be preceded by a fineness number. Older European pieces often carry lower standards:

• 925, Sterling or Ster.: at least 92.5% silver, the most common standard for silver jewelry.
• 958 or a Britannia mark: Britannia silver, a higher UK standard.
• 999 or Fine: fine silver, used for some jewelry and bullion.
• 900 or Coin: coin silver, common on older American pieces.
• 800, 830 or 835: lower standards found on many older European and Scandinavian pieces.
• 925 with a country, such as 925 Italy or 925 Thailand: sterling with the country of origin.

Platinum and palladium marks

Platinum marks in the US are tied to the share of pure platinum. A piece of at least 950 parts per thousand can simply be marked Platinum, while 900 and 850 pieces should carry the number, for example 900Pt or 850Plat. Lower-platinum alloys must spell out the other metals, such as 585 Pt. 415 Co., and pieces with less than 500 parts per thousand should not be called platinum at all.

Palladium is a platinum group metal too and uses Pd. or Pall., usually with a number such as 950 Pd. or 500 Pall. Be careful with the number alone: 950 can be platinum, palladium or a high-standard silver, and 750 can be gold or platinum. Always read the letters with the number, and if the piece is white, do not assume it is white gold, platinum or silver until it has been tested.

Maker's marks and hallmarks

Next to a purity mark you will often find a maker's mark: a name, initials or logo. In the US, a manufacturer or dealer who applies a gold or silver quality mark is required to add its trademark or name as well, so a purity mark with no maker's mark at all on a modern American piece is worth a second look. Searching the maker's name together with the word jewelry often tells you more about a piece than the purity mark alone.

In countries with official hallmarking, an independent assay office tests the piece and stamps its own mark. In the UK, for example, the compulsory hallmark has three parts: the sponsor's mark of the maker or importer, the fineness mark and the assay office mark, with an optional date letter. Many other countries use different systems, and some have no compulsory testing at all, so a missing hallmark tells you something about where a piece is from, not necessarily about its quality.

Where to look on a piece

Stamps are tiny, so start where makers usually put them. On rings, check the inside of the band, often at the bottom of the shank. On necklaces and bracelets, look on the clasp, the tag next to it, or the jump ring at the end. On earrings, check the posts, the backs and the hooks. On pendants, look on the bail or the back. On brooches, check the pin, the clasp and the back plate.

Worn marks are common. Rings that have been resized can lose part of a stamp, and clasps are often replaced, which means a mark on the clasp may describe the clasp but not the chain. US guides say that when a mark applies only to part of a piece, that should be made clear, but older and imported pieces do not always follow that rule. If the mark is on a part that could have been replaced, treat it as a weaker clue.

Why a mark is a clue, not proof

A stamp is a claim made by whoever applied it. Most are accurate, but fake and misleading marks exist, especially on pieces sold online or at markets, and a mark can be stamped onto plated base metal as easily as onto solid gold. Even accurate marks have tolerances: US rules allow a karat-marked piece to test slightly below its mark, by up to three parts per thousand for pieces without solder and seven with solder.

So use a mark as the starting point and look for consistency. Does the color fit the metal? Does a magnet leave it alone, as it should for gold, silver and platinum? Is there wear showing another color underneath? Does the weight feel right for the size? When a piece matters, ask a jeweler for an acid or XRF test; XRF reads the surface, so a thick plating can still fool it, and only a fire assay is fully conclusive. Keep a photo of each mark before cleaning or repairs.

Where CaratAI fits

CaratAI can help you read stamps quickly. Take a clear, close photo of the mark and the piece, and the app suggests what the mark likely means, which metal and fineness it points to, and whether it looks like a purity, plating or maker's mark.

For more detail, the free Hallmark Quick Reference on this site lists the common marks by metal, and the free Gold Melt Value Calculator turns a karat mark and a weight into a melt-value estimate once you add today's gold price. All of these are estimates and guides, not a substitute for a jeweler's test, an assay or an appraisal.

Frequently asked questions

What does 925 mean on jewelry? It means sterling silver, at least 92.5% pure. It does not mean gold, even on a gold-colored piece; that is usually gold-plated or vermeil silver.

What does 14K or 585 mean? Both mean 14 karat gold, 58.5% pure gold. 18K and 750 mean 75% gold.

Is a piece marked GF or GP real gold? It has real gold only on the surface, over a base metal, so its gold value is low.

What if my jewelry has no stamp? Many older, handmade or imported pieces are unmarked, and marks wear away. A jeweler can test the metal.

Can a stamp be fake? Yes. Treat every mark as a clue and test pieces that matter before you buy or sell.