About the Carat to Gram
This converter turns metric carats, the standard unit used to weigh diamonds and other gemstones, into grams and jewelers' points. It is built for anyone pricing, insuring, or comparing loose stones who needs an exact metric weight rather than the carat figure printed on a certification.
How It Works
Enter a carat value and the tool multiplies it by the fixed conversion factor of 0.2 grams per carat to get the weight in grams, and by 100 to get points. Points are simply carats expressed as hundredths, a convention jewelers use for describing small stones without decimals.
Formula & Methodology
Because 1 metric carat is defined as exactly 0.2 grams, the gram conversion is a straight multiplication with no rounding built into the underlying math (the display rounds to 4 decimal places). The points conversion follows the same logic in the other direction: multiplying carats by 100 turns a decimal weight into a whole-number-friendly scale, since 1 carat equals 100 points by definition.
Examples
A 1-carat diamond
Entering 1 carat returns 0.2 grams and 100 points, matching the standard reference weight jewelers use as a baseline for pricing per carat.
A 0.35-carat accent stone
Entering 0.35 carats returns 0.07 grams and 35 points, the kind of figure that appears on a certification for a small side stone in a ring setting.
Advantages
- Removes the need to remember or look up the 0.2 gram-per-carat conversion factor.
- Converts directly to jeweler's points, matching how small stones are commonly described in the trade.
- Gives a precise gram figure useful for shipping weight, insurance appraisal, or scale verification.
Common Mistakes
- Confusing carat (gemstone weight) with karat (gold purity out of 24), which are unrelated measurements despite the similar spelling.
- Assuming carat weight alone determines a diamond's value, when cut, clarity, and color also factor heavily into pricing.
- Reading a jeweler's scale in grams and forgetting to convert back to carats before comparing it to a certificate.
Edge Cases to Watch For
- Very small stones (under 0.01 carats) will show a points value under 1, which jewelers would typically describe using the carat decimal instead.
- The calculator does not distinguish between metric carats and older, now-obsolete carat definitions used before 1913, which varied slightly by country.
- Points are a jewelry-trade convention for diamonds specifically; the term is used less consistently for colored gemstones.
Common Use Cases
- Jewelry buyers checking that a gemstone's certified carat weight matches its gram weight on a home scale.
- Jewelers and appraisers converting between carats and points when describing small diamonds to clients.
- Shippers or insurers who need a gemstone's weight in grams for postal or insurance documentation.