Those tiny numbers and symbols stamped inside your ring or on your necklace clasp are not random. They are hallmarks — official stamps that tell you exactly what you are wearing. Understanding these marks helps you verify quality and authenticity.
Gold Hallmarks
Gold jewelry is stamped with marks indicating purity:
- 375: 9K gold (37.5% pure gold) — Common in UK jewelry
- 417: 10K gold (41.7% pure gold) — Minimum gold standard in the US. See our 10K vs 14K comparison
- 585: 14K gold (58.5% pure gold) — Most popular in the US for fine jewelry
- 750: 18K gold (75% pure gold) — Premium quality, deeper color
- 916: 22K gold (91.6% pure gold) — Common in Middle Eastern and Indian jewelry
- 999: 24K gold (99.9% pure gold) — Pure gold, too soft for most jewelry
Learn more about gold purity in our gold karats guide.
Silver Hallmarks
Sterling silver and other silver alloys:
- 925: Sterling silver (92.5% pure silver) — The standard for silver jewelry. Full details in our sterling silver guide
- 950: Britannia silver (95% pure silver) — Higher purity, slightly softer
- 900: Coin silver (90% pure silver) — Found in antique pieces
- 800: Continental silver (80% pure silver) — Common in European antique jewelry
Platinum Hallmarks
- 950: 95% platinum — Standard for fine platinum jewelry
- 900: 90% platinum — Common in vintage pieces
- 850: 85% platinum — Less common
- PT or PLAT: Sometimes stamped alongside the number to confirm platinum
Other Common Stamps
- GF or 1/20: Gold-filled (a thick layer of gold bonded to base metal, more durable than plating)
- GP or GEP: Gold-plated or gold electroplated (thin layer of gold over base metal)
- RGP: Rolled gold plate (similar to gold-filled but thinner layer)
- SS: Stainless steel
- STER: Sterling silver (abbreviation, same as 925)
- CZ: Cubic zirconia (indicates the stone is lab-created)
Maker Marks
Besides purity stamps, jewelry may have:
- Brand or maker logo: Identifies the manufacturer
- Country marks: Some countries require origin stamps
- Date letters: In British hallmarking, a letter indicates the year of assay
- Assay office marks: The testing office that verified the metal purity
How to Read Hallmarks
- Location: Inside the band for rings, on clasps for necklaces and bracelets, on posts for earrings
- Tool: A jeweler’s loupe (10x magnification) makes reading stamps easy
- Condition: Stamps may wear over time, especially on frequently worn pieces
- Missing stamps: Very old, handmade, or costume jewelry may have no hallmarks
Red Flags
- No stamp at all on jewelry sold as gold or silver — ask for verification
- A "925" stamp on a piece sold as solid gold — it is actually silver
- "Gold" or "silver" color with no purity stamp — likely plated or costume
- Stamps that look crooked, shallow, or inconsistent — possible counterfeit
Learn more about authenticating jewelry in our buyer’s guide. Shop verified quality at Biovlia with complimentary shipping on every order.
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