Understanding Precious Metal Purity Marks
Valuation Tips
Purity marks, also called hallmarks, tell you exactly what metal content is in your jewelry or bullion. Understanding these marks is essential for collectors and investors.
Gold Purity
Gold purity is measured in karats (not to be confused with carats for gemstones):
| Karat | Purity | Common Uses |
|---|---|---|
| 24K | 99.9% | Bullion, some Asian jewelry |
| 22K | 91.7% | High-karat jewelry, bullion coins |
| 18K | 75.0% | Fine jewelry worldwide |
| 14K | 58.3% | Popular in U.S. jewelry |
| 10K | 41.7% | Minimum legal "gold" in U.S. |
| 9K | 37.5% | Common in UK jewelry |
Gold Hallmarks by Country
- USA - "14K", "585", "14KT"
- UK - Crown, fineness, assay office mark, date letter
- France - Eagle head (18K), owl (imported)
- Italy - Star, number (750 for 18K)
Silver Purity
| Standard | Purity | Marks |
|---|---|---|
| Fine Silver | 99.9% | .999, "Fine Silver" |
| Sterling Silver | 92.5% | .925, "Sterling", lion passant (UK) |
| Coin Silver | 90.0% | .900 |
| Britannia Silver | 95.8% | .958 |
Platinum Purity
- 950 - 95% pure, most common for jewelry
- 900 - 90% pure
- 850 - 85% pure
- PLAT or PT - Must be at least 950 in U.S.
Common Misleading Marks
Be aware of marks that don't indicate precious metal:
- GP, GEP, RGP - Gold Plated, Gold Electroplated, Rolled Gold Plate
- GF - Gold Filled (layer of gold over base metal)
- HGE - Heavy Gold Electroplate
- 925 on gold-colored items - Sterling silver that's been gold-plated
- Vermeil - Sterling silver with gold plating
Testing Metal Purity
- Acid Testing - Traditional method using acid reactions
- XRF Analysis - X-ray fluorescence for accurate, non-destructive testing
- Specific Gravity - Measuring density
- Electronic Testers - Quick but less accurate
Recording Purity in BigStash.app
When adding items to BigStash.app, record the purity marking. Our system uses this information to calculate accurate melt values based on current precious metal prices.