Carats to Grams Converter
Convert gemstone weight from Carats (ct) to Grams (g) with high precision. Designed for jewelers, gemologists, and investors dealing with precious stones.
About
In gemology, precision is financially critical. The Metric Carat (ct) was adopted in 1907 to standardize gemstone weighing, replacing a variety of local units based on carob seeds. One carat is legally defined as exactly 200 milligrams (0.2 grams). Even a discrepancy of a hundredth of a carat (points) can drastically alter the market value of diamonds, rubies, and sapphires.
This tool converts Carats to Grams, and vice versa, maintaining a high decimal precision (up to 4 places). While grams are the standard scientific unit for mass, the jewelry trade operates almost exclusively in carats for stones. Understanding the gram equivalent is often necessary for shipping, specific gravity testing, or when incorporating stones into metal settings where total piece weight is measured in grams.
Formulas
The relationship between the metric carat and the gram is linear and fixed by international standards.
Conversely, to find carats from grams:
Reference Data
| Stone Size (Carats) | Weight (Grams) | Weight (Milligrams) |
|---|---|---|
| 0.01 ct (1 point) | 0.002 g | 2 mg |
| 0.05 ct (5 points) | 0.010 g | 10 mg |
| 0.10 ct (10 points) | 0.020 g | 20 mg |
| 0.25 ct (Quarter) | 0.050 g | 50 mg |
| 0.50 ct (Half) | 0.100 g | 100 mg |
| 0.75 ct | 0.150 g | 150 mg |
| 1.00 ct (Solitaire) | 0.200 g | 200 mg |
| 1.50 ct | 0.300 g | 300 mg |
| 2.00 ct | 0.400 g | 400 mg |
| 5.00 ct | 1.000 g | 1,000 mg |
| 10.00 ct | 2.000 g | 2,000 mg |
| 100.00 ct | 20.000 g | 20,000 mg |
| 3,106 ct (Cullinan) | 621.35 g | 621,350 mg |