This Presidium® electronic gemstone gauge accurately measures loose or set stones—even those with deep girdles or set in deep mountings—and instantly converts millimeters to carats. An easy-to-read digital display indicates ID and OD from 0–25mm with .01mm accuracy, and the gauge includes a jewelry attachment for measuring depths of stones in settings. It features auto shut-off to conserve battery use. A 3-volt battery, protective case, and gemstone weight estimation table are included.