What Do the Numbers Stamped on Jewelry Mean?

What do the numbers on jewelry mean?

A number stamped on jewelry is its metal purity, written in parts per thousand. So 750 = 75.0% gold (18K), 585 = 58.5% gold (14K), and 925 = 92.5% silver (sterling). A number alone means solid metal. A number with letters after it — 18K GP, 14K GF — means the gold is only a surface layer. The number says nothing about any gemstones; those are identified separately.

Full jewelry stamp chart

Every stamp above links to its full page in the hallmark directory, with value notes and look-alikes.

Gold numbers: 375, 417, 585, 750, 916, 999

Gold purity is the karat expressed as parts per thousand. The higher the number, the more pure gold — and the softer and more valuable the piece:

• 375 — 9K, common in the UK; 37.5% gold.
• 417 — 10K, the US minimum to be called "gold"; hard and affordable.
• 585 — 14K, the most common US fine-jewelry gold.
• 750 — 18K, the global standard for luxury gold.
• 916 — 22K, common in South and East Asian gold.
• 999 — 24K, near-pure gold, usually bullion rather than jewelry.

Platinum numbers: PT950 and PT900

Platinum is stamped with PT (or PLAT) and its purity. PT950 (95% platinum) is the fine-jewelry standard; PT900 (90%) is common in vintage and Japanese pieces. Platinum is denser and pricier per gram than gold, so a platinum ring feels noticeably heavy for its size.

Silver numbers: 925 and 999

925 means sterling silver — 92.5% silver, the durable everyday standard. 999 is fine silver (99.9%), softer and used for bullion and some artisan pieces. If a gold-colored item is stamped 925, it's gold-plated or vermeil over silver, not solid gold — the 925 describes the silver base.

Letters: GP, GF, RGP, GEP — plated, not solid

A number followed by letters means the gold is only a coating over a cheaper base metal:

• GP — gold-plated: a thin electroplated layer.
• GF / 1/20 12K GF — gold-filled: a thicker mechanically bonded layer, more durable than plating.
• GEP — gold electroplate; HGE — heavy gold electroplate.
• RGP — rolled gold plate, an older term for gold-filled.

These carry little melt value. Solid gold is stamped with a number alone (375, 585, 750) or a plain karat mark (14K, 18K) with no trailing letters.

Where to find the stamp

• Rings — inside the band (the shank), opposite the setting.
• Necklaces & bracelets — on the clasp or a small tag next to it.
• Earrings — on the post or the back of the setting.

Stamps are tiny — use a magnifier or a phone camera zoomed in under bright light. Can't make it out? Photograph it and let the app read it.

No number stamped? What that means

A missing stamp doesn't automatically mean fake. Older pieces, handmade items, resized rings (where the stamp was polished off), and jewelry from regions without mandatory hallmarking can be solid precious metal with no mark. Confirm it with weight, a magnet (precious metals aren't magnetic), an acid or electronic test, or a jeweler. Once you know the metal and purity, estimate what the piece is worth at today's price.