The easy-to-read millimetre and carats scale eliminate eye fatigue to minimize human error. Even a small miscalculation can be costly when dealing in highly priced goods. The Dial Guage measures from 0.0 to 23.0 mm in 0.1mm / divisions. One revolution equals 10 mm. The hardened anvils resist wear and maintain accuracy for much longer periods. Only the Dial Guage incorporates the latest state-of-the-art patented non-metallic lubrication free rack and pinion technology. Instrumental Error +0.05 mm. Zeroing a simple realignment is all thats required. The one and only Gemstone Guage that directly provides dual measurements in millimetre and combining clear and instant carats conversion. There are no complicated adjustments to make, simply hold the gauge in your hand, move slider with the thumb and measure stones or mountings using anvils wedge shaped points - projecting probe high setting jewelery attachment. Ideal for calibrating melee & matching gemstones. High setting jewelery attachment included. Size : L-97mm x W-61mm x H-16mm Weight : 100 gms 1 year factory warranty.