Feature: 1. Quick Identification: The refractometer can quickly and accurately identify a variety of single and double gemstones, helping to identify diamonds, moissanite, etc. 2. Strong Practicality: The primary use of the portable gemstones refractometer is to measure the angle at which light is bent or refracted through the stone. 3. Specially Designed: This refractometer is specially designed to measure the refractive index of gemstones and materials. 4. High Accuracy: Professional gemstones refractometer has high accuracy, small size, easy portability and easy operation. 5. Clear Display: The jewelry gemstones refractometer has a clearly visible display for easy reading. Specification: Item Type: Portable Gemstones Refractometer Material: Glass, ABS Product size:Approx. 128 x 60 x 32mm / 5.0 x 2.4 x 1.3in Measuring Range: 1.30 to 1.81 Minimum Division Value: 0.01 Liquid: Refractive Oil (Shipped with Liquid) Flashlight Battery: 1 x 1.5V AA Battery (Shipped Without Battery) Weight: Approx. 590g / 20.8oz. Package List: 1 x Portable Gemstones Refractometer1 x Flashlight1 x Refractive Oil1 x Box1 x User Manual Note: 1.The refractive index of gemstones is a very important optical parameter. The gloss of the gemstones can be determined by this parameter. Since different gemstones have a fixed refractive index, all kinds of gems can be determined according to the refractive index. Birefringence can also be measured. This parameter can be used to determine whether a gemstones is uniaxial or biaxial.2.Shipped with liquid, shipped without battery.