Gold Karat Purity Glossary: 24K, 22K, 18K, 14K & 10K Explained
Bikash Roy
Online Research Specialist · SEO Strategist · Web Developer
Bikash personally verifies every calculator against official standards (WHO, NIH, government data). Online research specialist, SEO strategist, and web developer with 10+ years building accurate digital tools.
Full bio →What “Karat” Actually Means
Karat (written with a K, not to be confused with carat, the gemstone weight unit) measures how much pure gold is in a piece of jewelry or bullion. The scale runs from 0 to 24, where 24 karat represents essentially pure gold. Anything below 24K is an alloy — pure gold mixed with other metals like copper, silver, zinc, or palladium to make it harder and more affordable.
The math is simple: purity fraction = karat ÷ 24. A 14K item is 14 ÷ 24 = 58.3% pure gold by weight. The remaining 41.7% is other metal. This is exactly the formula used by the scrap gold calculator to convert karat and weight into melt value.
Karat-to-Purity Reference Table
| Karat | Purity (%) | Millesimal Fineness | Common Use |
|---|---|---|---|
| 24K | 99.9% | .999 | Bars, coins, investment bullion, some Asian jewelry markets |
| 22K | 91.7% | .916 | Middle Eastern and South Asian jewelry |
| 18K | 75.0% | .750 | Fine Western jewelry — engagement rings, luxury watches |
| 14K | 58.3% | .583 | Most common karat for everyday US jewelry |
| 10K | 41.7% | .417 | Minimum karat legally sellable as “gold” in the US |
Fourteen karat is bolded because it’s the karat most US consumers actually own — it balances a meaningful gold content with the durability everyday jewelry needs.
What Is Millesimal Fineness?
Millesimal fineness expresses purity in parts per thousand instead of a 24-point karat scale. A .999 stamp means 999 parts per 1,000 are pure gold — essentially the same statement as “24K,” just using a different scale. Fineness is the standard used internationally and by bullion markets: the LBMA’s Good Delivery standard requires gold bars to meet a minimum fineness of 995.0 parts per thousand, which is why large-scale bullion bars are marked closer to .995–.999 rather than a karat number. The APMEX Learning Center’s guide to fine gold covers the fineness scale in more depth if you’re comparing jewelry karat to bullion-grade purity.
Both scales describe the same thing. If you see a stamp like .585 instead of “14K,” it’s telling you the same purity — .585 rounds to the same 58.3% as 14K (jewelry marks are occasionally rounded slightly, so .583 and .585 both mean 14K in practice).
Why the Remaining Metal Matters
Every karat below 24K contains alloy metal that has essentially no scrap value. A 10K ring and a 24K ring of the same total weight are not close in melt value — the 10K piece has less than half the pure gold content. This is also why color varies by karat and alloy: white gold typically uses palladium or nickel in the mix, while rose gold uses more copper. The alloy changes the color and hardness, but only the karat number tells you how much actual gold you’re being paid for.
Reading a Stamp You Can’t Identify
US-made jewelry almost always carries a karat or fineness stamp somewhere on the piece — inside a ring band, on a clasp, or on the underside of a pendant. If a piece has no stamp at all, don’t guess. Unmarked gold should be tested by a jeweler before you rely on any karat assumption, since gold-plated and gold-filled items can look identical to solid gold at a glance. See the guide to selling scrap gold for the best price for how professional karat testing works.
From Karat to Dollars
Once you know your item’s karat, the only other inputs needed for a melt value are weight and the current gold spot price. Plug both into the scrap gold calculator to get an instant melt value, or see worked melt value examples by karat and weight for real number walkthroughs at several common karats. Melt value is only half the picture, though — what a buyer actually pays you is a percentage of that number. The dealer payout percentages guide breaks down what to expect from different buyer types.
If you’re also sorting through silver pieces, the same purity logic applies with different fineness marks (sterling is .925, not karat-based) — see the scrap silver calculator for that side of a mixed jewelry box.