Grams to Carats Converter
Convert mass from grams (g) to metric carats (ct) with precision for jewelers and gemologists. Includes gemstone weight reference.
About
Precision is the currency of the jewelry trade. A discrepancy of a fraction of a carat can alter the valuation of a gemstone by thousands of dollars. This converter translates mass from Grams (g) to Metric Carats (ct), adhering to the international standard where 1 carat equals exactly 200 milligrams. Jewelers, lapidaries, and gold traders use this calculation to finalize appraisals, certify gem weights, and determine shipping insurance values. Unlike generic mass converters, this tool prioritizes decimal visibility to prevent costly transcription errors during high-stakes transactions.
Formulas
The metric carat is defined as exactly 200 milligrams. To convert from grams to carats, multiply the mass value by 5.
Where wct represents the weight in carats and wg is the weight in grams. Conversely, 1 g = 5 ct.
Reference Data
| Gemstone | Rough Density (g/cm3) | Typ. Cut Weight (ct) | Equiv. Mass (g) |
|---|---|---|---|
| Diamond (Round Brilliant) | 3.51 | 0.50 | 0.10 |
| Diamond (Solitaire) | 3.51 | 1.00 | 0.20 |
| Ruby (Pigeon Blood) | 4.00 | 2.50 | 0.50 |
| Sapphire (Kashmir) | 3.98 | 5.00 | 1.00 |
| Emerald (Colombian) | 2.76 | 1.25 | 0.25 |
| Amethyst | 2.65 | 10.00 | 2.00 |
| Opal (Black) | 2.10 | 3.00 | 0.60 |
| Pearl (South Sea) | 2.70 | 15.00 | 3.00 |
| Tanzanite | 3.35 | 4.00 | 0.80 |
| Gold Nugget (Small) | 19.32 | 24.00 | 4.80 |