Karat measures gold purity in 24ths: 24K is pure gold, 12K would be half gold, and anything lower is mostly other metal. Most of the world stamps jewelry with the equivalent millesimalnumber instead — parts per thousand — which is why an 18K ring usually says “750.” This chart decodes both.
Karat to purity chart
| Karat | Stamp | Purity | Typical use |
|---|---|---|---|
| 24K | 999 | 99.9% | Bullion bars and coins (Maple Leaf, Buffalo), Asian fine jewelry |
| 22K | 916 | 91.7% | Gold Eagles, Krugerrands, Sovereigns; Indian and Middle Eastern jewelry |
| 21K | 875 | 87.5% | Middle Eastern jewelry standard |
| 18K | 750 | 75.0% | Fine jewelry worldwide; luxury watches |
| 14K | 585 | 58.3% | The dominant US jewelry standard |
| 10K | 417 | 41.7% | Minimum to be sold as 'gold' in the US; class rings, budget jewelry |
| 9K | 375 | 37.5% | UK and Ireland minimum standard |
| 8K | 333 | 33.3% | German minimum standard |
To convert any karat yourself: divide by 24. So 14 ÷ 24 = 0.583 — a gram of 14K contains 0.583 g of fine gold. That purity number plugs straight into the melt formula in how to calculate scrap gold value, or pick the karat directly in the scrap gold calculator. Live per-gram prices for each karat: 10K, 14K, 18K, 22K, 24K.
Why alloy at all?
Pure gold is soft enough to scratch with a coin. Alloying with copper, silver, nickel or zinc adds durability — and changes color: more copper gives rose gold, nickel or palladium gives white gold (usually rhodium-plated on top). Color says nothing about karat; an 18K rose ring and an 18K white ring contain identical gold.
The stamps that mean “almost no gold”
These marks look official but signal plated or filled items with negligible melt value:
- GF or 1/20 12K GF— gold-filled: a thin gold sheet bonded over brass; gold is ~2–5% of the item’s weight.
- GP, GEP, RGP, HGE — gold plated / electroplate / heavy gold electroplate: a microns-thick coating, essentially worthless as metal.
- 1/10 10K and similar fractions — filled, with the fraction telling you how little.
Unmarked or suspect pieces deserve a real test — magnet, density, acid or XRF — covered in how to tell if gold is real.
Frequently asked questions
What does 750 mean on jewelry?
750 is the millesimal mark for 18 karat gold — 750 parts per thousand, or 75% pure. Likewise 585 means 14K and 417 means 10K.
Is 24K gold really 100% pure?
Effectively. 24K denotes at least 99.9% (.999 fine); premium bullion like the Canadian Maple Leaf is refined to .9999. No commercial gold is literally 100.000% pure.
What is the lowest karat that counts as gold?
It depends on the country: the US requires 10K to be sold as gold, the UK and Ireland allow 9K, and Germany historically allows 8K (333). Below those thresholds it is legally just gold-colored alloy.