585, 750, 925, PLAT — the tiny stamps inside a ring shank or on a clasp tell you what a piece is made of, and often who made it and where. Here’s how to read them — and what to do when a mark is missing, worn, or too good to be true.
A hallmark is a small stamp struck into precious-metal jewelry that certifies its metal content — for example 585 for 14K gold or 925 for sterling silver. Alongside the purity mark you may find a maker’s mark (who made it), an assay mark (where it was tested) and, on older British pieces, a date letter (when).
Where to look: inside the ring shank, on the clasp or tag of necklaces and bracelets, on the post or back of earrings, and on the case back of watches. A 10× loupe helps — most marks are under a millimeter tall.
| Stamp | Karat | Pure gold | Notes |
|---|---|---|---|
| 417 | 10K | 41.7% | Minimum to be sold as gold in the U.S. |
| 585 | 14K | 58.5% | The everyday standard for fine jewelry. |
| 750 | 18K | 75% | Luxury pieces — richer color, softer metal. |
| 916 | 22K | 91.6% | Common in Middle Eastern & South Asian jewelry. |
| 999 | 24K | 99.9% | Essentially pure — too soft for most jewelry. |
Warning marks that are not solid gold: GF or 1/20 14K GF (gold-filled), GP, GEP or HGE (gold-plated), and 925 with gold color (vermeil — gold over silver). These contain only a thin layer of gold. More on purity in our gold karats guide and platinum vs. white gold.
| Stamp | Metal | Purity | Notes |
|---|---|---|---|
| 925 / STERLING | Silver | 92.5% | The sterling standard. |
| 800 / 900 | Silver | 80–90% | Continental & coin silver, common in antiques. |
| PLAT / PT950 / 950 | Platinum | 95% | The usual platinum standard for jewelry. |
| PT900 / IRIDPLAT | Platinum | 90% | Frequent in vintage & Art Deco pieces. |
| PD950 | Palladium | 95% | Lighter platinum-family metal. |
Beware “nickel silver” or “German silver” — despite the name, they contain no silver at all.
Initials or a symbol identifying the workshop — and on signed pieces, names like Cartier or David Webb that multiply value. See our guide to designer & signed jewelry.
National symbols certifying official testing: Britain’s lion passant for sterling, France’s eagle’s head for 18K gold, Swiss marks on watch cases. Useful for dating and locating a piece.
British hallmarks include a letter whose font and shield shape pin the year of assay. Designer pieces often carry serial numbers — a key authenticity check.
A hallmark is a strong clue, not a guarantee. Marks wear thin with decades of use, disappear when a ring is resized, and were never required on many antique pieces. Counterfeit stamps also exist — plated pieces struck with a false 585 or 750.
How to examine a piece at home:
The metal is 58.5% pure gold — the European stamp for 14-karat gold. Likewise 750 = 18K, 417 = 10K, 916 = 22K.
925 is sterling silver (92.5% silver), not gold. A gold-colored piece stamped 925 is vermeil — a layer of gold over sterling silver.
Not necessarily. Many antiques predate stamping requirements, and marks wear off or vanish during resizing. Testing confirms what the metal really is.
Yes — both mean 75% gold. 750 is the European convention, 18K the American one. Many pieces carry either or both.
Yes. False purity stamps on plated pieces do circulate. Treat a mark as a clue and let acid or electronic testing confirm it.
Yes. We read the marks, test the metal and provide written appraisals for insurance, estate or resale — by mail, nationwide, with no obligation to sell.
Send a photo or mail the piece — we’ll read the marks, test the metal and put its value in writing. Honest and independent, since 1996.