Gemstone Weight Calculator and Stone ID Tool from Dendritics

Carat Weight Calculator. How to measure carats when a stone is mounted. Using our Proprietary Advanced Formula for Round, Emerald, Marquise, Radiant, and Oval cuts which takes into account the culet size, shape of the sides, roundness of the belly, variations in the girdle as well as table proportion.

Stone Identification. When your stone is loose, combine this same advanced mm-to-carat calculator with a measured gemstone weight to compute its specific gravity. Our Stone ID tool then combines this specific gravity with color and appearance to arrive at the most likely options of your stone's identity.




cet0 0
1 3
3 h1
lar1 p1
ush2 0
et0 1
tep1 0
4 t0
on4 4


Length Width



Girdle ...

 Select Stone
(Common stones first)

 Enter Weight

Your Answer
Will be here


0 Using the proprietary Dendritics Advanced Formula.
1 Using the relatively crude Standard Formula, with larger indicated uncertainty than on other cuts. You need only enter the basic Measurements and Belly Shape.
2 Square cushion. Enter corner & belly measurements as Length and Width. Also uses the Standard Formula. You need only enter the basic Measurements and Belly Shape.
3 Pear and Heart cuts. These are the only cuts to use Side Shape (curvature).
4 Cabochon, Spheroid and Octahedron. You need only enter the basic Measurements.
5 We hope you enjoy the updated, cleaner interface. The original version is here. Your suggestions are welcomed ()

Images and webpage designs by jb, © 2017 Dendritics Inc.