How to convert carats to grams
- Take the value in carats.
- Use the formula grams = carats ÷ 5.
- For example, 0.25 ct is 0.05 g.
About carats and grams
The metric carat is exactly 200 milligrams, so divide carats by 5 to get grams. A 1 ct diamond weighs 0.2 g, a half carat 0.1 g and a 5 ct stone 1 g.
Gemstones and pearls are weighed in carats, often to two decimals. Each hundredth of a carat is called a point, so a 0.25 ct stone is a 25-point stone and weighs 50 mg. Carat measures weight, not size: a dense stone of the same carat weight looks smaller than a light one.
Examples
- 0.25 ct (a quarter carat, or 25 points) is 0.05 g
- 1 ct (a one-carat diamond) is 0.2 g
- 5 ct (a five-carat stone) is 1 g
- 3,106.75 ct (the rough Cullinan diamond found in 1905) is 621.35 g
Carats to grams chart
| Carats (ct) | Grams (g) |
|---|---|
| 0.01 | 0.002 |
| 0.05 | 0.01 |
| 0.1 | 0.02 |
| 0.25 | 0.05 |
| 0.3 | 0.06 |
| 0.5 | 0.1 |
| 0.75 | 0.15 |
| 1 | 0.2 |
| 1.25 | 0.25 |
| 1.5 | 0.3 |
| 2 | 0.4 |
| Carats (ct) | Grams (g) |
|---|---|
| 2.5 | 0.5 |
| 3 | 0.6 |
| 4 | 0.8 |
| 5 | 1 |
| 10 | 2 |
| 15 | 3 |
| 20 | 4 |
| 25 | 5 |
| 50 | 10 |
| 100 | 20 |