Diamond, Gemstone & Bead Sizing Template Estimator Perfect for determining the size and carat weight of loose or mounted Diamonds including round, emerald, marquise, pear, and baguette shapes. Also determines millimeter sizes on round beads from 2mm to 13mm. Simply place the stone or bead to be measured on the appropriate outline to view the size. Size: 9" long x 4-1/2" wide Gemstone Estimator Gauge Simply place gemstone on the appropriate outline to determine the approximate weight