Carat to Gram Converter
Convert gemstone mass between carats, grams, milligrams and ounces.
How to Use the Carat to Gram Converter
This converter changes gemstone mass from carats into grams, milligrams and ounces. Enter the carat weight and the tool applies the metric carat definition of 1 carat = 0.2 grams.
Practical Example
A gemstone weighing 2.5 carats has a mass of 0.5 grams or 500 milligrams. The same mass is approximately 0.01764 ounces.
Factors That Affect the Result
The unit conversion is exact for metric carats, but physical gemstone size also depends on density, cut proportions and shape. Two stones with the same carat weight can therefore have different visible dimensions.
Frequently Asked Questions
How many grams are in one carat?
One metric carat equals exactly 0.2 grams.
Is carat the same as gold karat?
No. Carat measures gemstone mass, while karat describes gold purity.
Does carat weight determine gemstone size?
Not by itself. Density and cut shape affect how large a stone appears.
Understanding Carat and Gram Conversion
Carats are commonly used for gemstones, while grams and milligrams are broader metric mass units. One metric carat equals exactly 0.2 grams, so the conversion is a direct mass calculation rather than an estimate. This makes it useful when comparing jewelry specifications, gemstone weights or laboratory measurements expressed in different units.
Keep in mind that carat measures mass, not physical size. Two stones with the same carat weight can have different dimensions because of density, cut and proportions. When accuracy matters, use the stated weight from a calibrated scale and avoid confusing gemstone carats with gold karat, which describes purity rather than mass.