Gold Karats & Fineness Hallmarks
Jewelry & Precious Metals · 8 specs
Direct Answer
Precious metal fineness is standardized under ISO 9202 and national hallmark regulations in parts per thousand (millesimal fineness) and traditional karats (24ths of pure gold), defining the exact alloy ratios of pure 24K (999), 18K (750), 14K (585), 10K (417), Sterling Silver (925), and Platinum (950).
Source: ISO 9202:2019 Jewellery and precious metals — Fineness of precious metal alloys / Hallmarking Act 1973 / FTC Jewelry Guides · Last reviewed Aug 28, 2026
Specs
| Governing Standards | ISO 9202 / ISO 11426 (Fire Assay) / FTC 16 CFR Part 23 / UK Hallmarking Act |
| 24 Karat Gold (24K) | 99.9% Pure Gold | Millesimal Hallmark: 999 | Soft, malleable, rich orange-yellow (too soft for daily rings) |
| 18 Karat Gold (18K) | 75.0% Pure Gold + 25% Copper/Silver/Zinc | Hallmark: 750 | European luxury standard, rich color, durable |
| 14 Karat Gold (14K) | 58.3%–58.5% Pure Gold + 41.5% Alloy | Hallmark: 585 (or 14K) | US engagement ring benchmark (~90% market share) |
| 10 Karat Gold (10K) | 41.7% Pure Gold + 58.3% Alloy | Hallmark: 417 (or 10K) | Minimum legal standard to be called 'gold' in the USA |
| 9 Karat Gold (9K) | 37.5% Pure Gold | Hallmark: 375 | Legal minimum gold standard in the UK, Australia, and South Africa |
| Sterling Silver Standard | 92.5% Pure Silver + 7.5% Copper | Hallmark: 925 / STERLING | Balance gives silver tensile hardness |
| Fine Platinum Standard | 95.0% Pure Platinum + 5% Ruthenium/Iridium | Hallmark: 950 / PLAT | Dense (21.45 g/cm³), hypoallergenic |
Global Precious Metal Karat, Purity Percentage & Hallmark Matrix
| Karat Rating | Pure Gold Percentage | Parts per Thousand (Millesimal) | Standard Stamp / Hallmark | Metal Density (g/cm³) | Scratch & Wear Resistance |
|---|---|---|---|---|---|
| 24 Karat (24K) | 99.9% | 999 | 24K / 999 | 19.32 g/cm³ | Very Soft (Easily scratched / bends) |
| 22 Karat (22K) | 91.6% | 916 | 22K / 916 | ~17.8 g/cm³ | Soft (Middle Eastern & Indian traditional jewelry) |
| 18 Karat (18K) | 75.0% | 750 | 18K / 750 | ~15.5 g/cm³ | High (Fine luxury European jewelry standard) |
| 14 Karat (14K) | 58.3%–58.5% | 585 | 14K / 585 | ~13.1 g/cm³ | Very High (Optimal everyday hardness in USA) |
| 10 Karat (10K) | 41.7% | 417 | 10K / 417 | ~11.6 g/cm³ | Extremely Hard (Resistant to bending, paler tone) |
| 9 Karat (9K) | 37.5% | 375 | 9K / 375 | ~11.2 g/cm³ | Extremely Hard (UK / Australian common retail) |
| Sterling Silver | 92.5% Silver | 925 | 925 / STERLING | 10.36 g/cm³ | Moderate (Prone to surface tarnish oxidation) |
| Platinum 950 | 95.0% Platinum | 950 | 950 / PLAT | 21.45 g/cm³ | Ultra-Durable (Displaces metal rather than loses it) |
Yellow Gold vs White Gold vs Rose Gold Metallurgy
- Yellow Gold: Blended with equal proportions of pure silver and copper to retain natural warm gold hues.
- White Gold: Alloyed with white metals (nickel, palladium, or manganese) and electroplated with Rhodium (0.5–1.0 micron) to achieve a mirror chrome-white finish. Rhodium naturally wears over 2–4 years, requiring periodic re-dipping.
- Rose Gold: Alloyed with a higher ratio of copper (e.g. 18K Rose Gold = 75% Gold + 22.25% Copper + 2.75% Silver), producing an antique pinkish-red hue with exceptional structural hardness.