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 RefractometerMaterial: Glass, ABSProduct size:Approx. 128 x 60 x 32mm / 5.0 x 2.4 x 1.3inMeasuring Range: 1.30 to 1.81Minimum Division Value: 0.01Liquid: 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 ManualNote: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.