Karat measures purity in twenty-fourths: 24K is pure gold, so every karat below that swaps a fraction of gold for strengthening metals (copper, silver, nickel, zinc). The swap changes three things at once: value per gram, color, and hardness — pure gold is soft and deeply yellow; lower karats are paler and far tougher.
| Karat | Gold % | Stamp | Typical use |
|---|---|---|---|
| 24K | 99.9% | 999 / 24K | Bullion bars & coins; too soft for most jewelry |
| 22K | 91.7% | 916 / 22K | Coins (Eagles, Sovereigns), South Asian bridal jewelry |
| 18K | 75.0% | 750 / 18K | Fine jewelry, luxury watches — rich color, good strength |
| 14K | 58.3% | 585 / 14K | The US jewelry standard — best durability/value balance |
| 10K | 41.7% | 417 / 10K | Budget & high-wear pieces; the legal minimum “gold” in the US |
Reading the stamps
US pieces are stamped in karats (14K, sometimes 14KP — “P” means plumb: exactly that purity). European pieces use fineness numbers: 750 means 750 parts per thousand = 18K; 585 = 14K; 916 = 22K; 999 = pure. Other marks to know: GP = gold plated, GF = gold filled, HGE = heavy gold electroplate — all surface treatments over base metal, worth a small fraction of solid gold; the melt calculator on this site does not apply to them.
Color is a karat clue, not a verdict
Yellow gold alloys with copper and silver; white gold with nickel or palladium (then usually rhodium-plated); rose gold with extra copper. A 14K piece is visibly paler than 18K in the same color family. But color alone cannot grade purity — only the stamp, an acid/XRF test, or a jeweler's word can. When selling, dealers test regardless of stamps.
Which karat should you buy?
For rings and daily-wear pieces, 14K is the engineer's answer — hard enough for decades, still majority gold. For heirloom and fine pieces worn gently, 18K's color and feel justify its price. 22K and 24K belong in coins and bars, where softness does not matter and purity is the whole point.