A hallmark is a set of stamps on a piece of jewelry or silverware that tells you what metal it is made of and how pure that metal is. In countries such as the United Kingdom, an independent assay office tests the item before marking it. In the United States, makers stamp their own quality marks under federal rules. Learning a few numbers and symbols lets you read most marks in seconds.
Hallmark versus quality mark
The term hallmark strictly means a mark applied by an independent testing office. It comes from Goldsmiths' Hall in London, where the Worshipful Company of Goldsmiths has tested and marked precious metal for centuries. In everyday use, people call any purity stamp a hallmark.
There are two broad systems:
- Third-party hallmarking. An assay office tests the metal and stamps it. The United Kingdom, Ireland, France, the Netherlands, Switzerland and several other countries work this way, though rules differ.
- Maker's quality marks. The manufacturer or seller stamps the purity, and the law punishes false marks. The United States, Canada and many other countries use this system.
Fineness numbers
Most marks today use millesimal fineness, which gives the precious metal content in parts per thousand.
| Mark | Metal | Meaning |
|---|---|---|
| 375 | Gold | 9K, 37.5 percent gold |
| 417 | Gold | 10K, 41.7 percent gold |
| 585 | Gold | 14K, 58.5 percent gold |
| 750 | Gold | 18K, 75 percent gold |
| 916 | Gold | 22K, 91.6 percent gold |
| 999 | Gold or silver | Fine (99.9 percent) |
| 800 | Silver | 80 percent silver, common in older European pieces |
| 925 | Silver | Sterling silver |
| 958 | Silver | Britannia silver |
| 900 | Platinum or silver | 90 percent platinum, or coin silver |
| 950 | Platinum or palladium | 95 percent pure |
| 500 | Palladium | 50 percent palladium |
You may also see 583 for 14K, an older standard, and 333 for 8K, used in Germany and a few other countries. Karat stamps such as 14K, 18K or 18ct express the same gold content in karats. The yellow gold page explains the karat system.
UK hallmarks
The United Kingdom has one of the oldest hallmarking systems. A statute of 1300 under Edward I required silver to meet the sterling standard and be marked with a leopard's head. Date letters were introduced in London in 1478. Today the Hallmarking Act 1973 governs the system, and four assay offices operate: London, Birmingham, Sheffield and Edinburgh. Others, such as Chester, Exeter and Glasgow, closed in earlier centuries or the twentieth century, and their marks appear on antiques.
A modern UK hallmark has three compulsory parts:
- The sponsor's mark, the initials of the maker or company responsible, inside a shield.
- The fineness mark, the millesimal number inside a shield whose shape shows the metal.
- The assay office mark: a leopard's head for London, an anchor for Birmingham, a rose for Sheffield and a castle for Edinburgh.
Optional marks include a date letter, which gives the year of marking, and traditional fineness symbols. These are the lion passant for sterling silver (a lion rampant for Edinburgh), the figure of Britannia for Britannia silver, a crown for gold, an orb for platinum and the head of Pallas Athene for palladium. The date letter was compulsory until 1999. Collectors use it to date antique silver, since each office used a cycle of letters in changing fonts and shield shapes.
UK law requires items above set weights to be hallmarked before they can be described as gold, silver, platinum or palladium. The exemption weights are 1 gram for gold and palladium, 7.78 grams for silver and 0.5 grams for platinum. Palladium joined the list in 2010.
The UK also accepts the Common Control Mark (CCM) under the international Hallmarking Convention, signed in Vienna in 1972. Items tested in a member country carry a CCM showing a balance scale with the fineness number and are accepted in other member countries without retesting.
US quality stamps and FTC rules
The United States has no national assay office. The National Gold and Silver Stamping Act of 1906 and the Federal Trade Commission's Guides for the Jewelry, Precious Metals, and Pewter Industries set the rules.
- A gold item must be at least 10K to be marked or sold as gold. Marks may be in karats (14K) or fineness (585).
- Silver may be marked "sterling," "sterling silver" or 925 only if it is at least 92.5 percent silver. "Coin" or "coin silver" means at least 90 percent.
- An item can be marked simply "platinum" if it is at least 95 percent platinum. Lower platinum content must be stated, such as 900Plat. or 850Plat.
- When a maker stamps a quality mark on gold or silver, the item must also carry the maker's trademark, registered or applied for with the US Patent and Trademark Office, so the responsible party can be identified.
The word "plumb" after a karat mark, as in "14K plumb," means the gold meets the stated karat with no allowance for under-karat solder.
The FTC guides also cover layered metals. Marks such as GF (gold-filled), RGP (rolled gold plate), GP or GEP (gold-plated or gold electroplate) and HGE (heavy gold electroplate) describe base metal or silver with a gold layer, not solid gold. Vermeil means sterling silver with a gold coating of at least 10K and a minimum thickness. The silver page covers related silver terms.
Other national marks
Many countries add their own symbols. France uses small figures such as an eagle's head on 18K gold and the head of Minerva on silver. Older Russian pieces carry a zolotnik number (56 for 14K, 84 for 875 silver). The Netherlands uses a lion and other figures by standard. Indian gold jewelry has a hallmarking system run by the Bureau of Indian Standards, using marks such as 22K916 and 18K750. Reference books of marks help identify antique pieces from these systems.
How to read a mark
- Look inside the ring shank, on a clasp or tag, or on the back of a pendant. Use a 10x loupe.
- Find the number or karat stamp. That tells you the metal and purity.
- Look for a maker's mark or trademark next to it.
- On UK and other hallmarked pieces, look for the assay office symbol and date letter.
- Check for words such as GF, GP, EP or "plated," which mean a coating only.
Platinum marks may read PT950, PLAT or 950 Plat. Palladium marks read PD950 or 950 Pd. The platinum and palladium pages describe those standards.
Fake and misleading stamps
A stamp is easy to strike. Counterfeit and misleading marks exist, especially on items sold online and in unregulated markets. Common warning signs include:
- A karat or fineness mark with no maker's mark next to it, on a piece sold in the United States.
- A UK-style hallmark that is blurred, misaligned or missing the assay office mark.
- Marks such as "18KGP," "HGE" or "925 gold" that combine terms in confusing ways.
- A mark that does not match the weight or color of the piece.
Third-party hallmarking protects buyers because the metal has been tested. With maker's marks only, the stamp is a claim. When in doubt, a jeweler can test the metal with acid tests, an electronic tester or X-ray fluorescence (XRF), which reads metal composition without damage. Plated items need a test that goes below the surface. The jewelry metals overview and the metallurgy glossary explain the metals and terms behind each mark.
Frequently asked questions
What does 750 mean on jewelry?
It means 750 parts per thousand gold, which is 18K or 75 percent gold.
Is a 925 stamp always sterling silver?
It should be. In most countries a 925 mark is a legal claim of sterling silver. Fake marks exist, so a jeweler can test the metal if you are unsure.
What do the symbols on British silver mean?
They usually show the maker, the silver standard (925 and often a lion passant), the assay office (such as an anchor for Birmingham) and a date letter for the year of marking.
Why does my jewelry have no hallmark?
Many items are unmarked because they are below the legal weight thresholds, the mark wore off, it was removed during resizing or the piece was handmade without stamping. A jeweler can test the metal.