7 Blades Fan Gauge for measuring stones & Diamond, Jewelry Tool Use the diamond stone gauge to measure stones and also mounting sizes Folds to the size of a pocket knife and measures six shapes  Round from 0.01 to 6.0ct Oval from 0.75 to 3.0ct Marquise from 0.02 to 3.0ct Pear from 0.10 to 3.0ct Emerald from 0.02 to 3.0ct Cushion from  0.02 to 3.0ct Gauge Measures 3.52" Inches closed Measurements are in carat weight