Karat (K) tells you the share of pure gold in a piece, out of 24 parts: 14K is 14 parts gold out of 24, about 58.5%. Carat (ct) is a weight for diamonds and gems, and one carat is 200 milligrams (0.2 gram).
Two words that sound the same
“Karat” and “carat” sound alike, and people mix them up all the time. They measure completely different things:
- Karat (K or Kt) tells you how pure the gold is.
- Carat (ct) tells you how much a diamond or other gemstone weighs.
A ring stamped “14K” with a “1 ct” diamond has 14-karat gold and a one-carat stone. The first number affects the gold value. The second affects the stone’s value. Neither one tells you how much the ring weighs.
Outside the US, you may see “carat” used for gold purity too, as in “18 carat gold”. If you see it on gold, it means the same as karat.
What karat means
Karat is a scale out of 24. Pure gold is 24 karat. Anything less is gold mixed with other metals, called an alloy, to make it harder and change its color.
To find the share of pure gold, divide the karat by 24:
| Karat | Parts gold out of 24 | Gold content | Common number stamp |
|---|---|---|---|
| 24K | 24 | 99.9% or more | 999 |
| 22K | 22 | 91.7% | 916 |
| 18K | 18 | 75% | 750 |
| 14K | 14 | 58.3% to 58.5% | 585 or 583 |
| 10K | 10 | 41.7% | 417 |
US rules from the FTC’s Jewelry Guides say gold below 24 karat should be described with its karat, such as “14 Karat Gold” or “14K”. See what do gold stamps mean? for the number stamps and the marks that mean an item is only plated.
Why karat matters when you sell
When you sell gold, the buyer pays for the pure gold inside. So a 10-gram 18K bracelet holds more gold than a 10-gram 10K bracelet:
- 10 g × 75% = 7.5 g of pure gold
- 10 g × 41.7% = 4.17 g of pure gold
Enter the weight and karat in the gold calculator to see the melt value. Melt value is what the pure gold is worth at today’s price. A buyer will offer a share of that.
What carat means
A carat is a unit of weight for diamonds and gems. Under the FTC’s Jewelry Guides, one carat equals 200 milligrams, or 0.2 gram. A carat is split into 100 “points”, so a 50-point diamond is half a carat (0.50 ct).
Jewelry is sometimes marked with the stone weight, such as “1/2 CT TW”. “TW” means total weight: all the stones added together, not one stone. The FTC guides say a weight given as a fraction, like 1/2 carat, should come with a note that it isn’t exact.
Carat weight is only one part of a diamond’s value. Cut, color and clarity matter too, which is why two stones of the same carat weight can be worth very different amounts.
Carat weight and gold weight
Because a carat is a weight, you can work out how much the stones add to a piece:
- 1 carat = 0.2 gram
- 0.5 carat = 0.1 gram
That sounds small, but it matters for larger stones or pieces with many stones. If you weigh a ring with its stones in, you are including stone weight that a scrap buyer won’t pay for as gold. See selling gold jewelry with diamonds or stones and how to weigh gold at home.
Quick summary
| Karat (K) | Carat (ct) | |
|---|---|---|
| Measures | Gold purity | Gemstone weight |
| Scale | Out of 24 | 1 ct = 0.2 gram |
| Where you see it | Stamped on the metal | On tags, receipts, grading reports, sometimes inside a band |
| Affects | Gold melt value | Stone value |
These figures are for estimating only. A buyer’s test of your gold, and an expert’s look at your stones, decide what you are paid.
- 16 CFR 23.3: Misrepresentation as to gold content (FTC Jewelry Guides)
- 16 CFR 23.18: Misrepresentation of weight and "total weight" (FTC Jewelry Guides)
Last reviewed October 31, 2026. This guide is general information, not legal, tax or financial advice.