2019 New gem instrument gem tool refractometer diamond detector external with light source measurement range 1.30-1.81ri i88 Gem Instrument Gem Tool Refractometer Diamond Detector External with Light Source Measurement range 1.30-1.81RI I88 Features: 1. All kinds of gems can be determined according to the index of refractive index, because different gemstones have fixed refractive index. 2. This parameter can be used to determine whether a gem is a uniaxial crystal or a biaxial crystal. 3.Unique design, extremely low power consumption and easy to carry. 4.High quality and high accuracy measurement results. 5.Through strict quality and safety standard test, long-term service life. Product specifications: 1.Measurement range: 1.30 ~ 1.81RI. 2.Minimum dividing value: 0.01RI. 3.Size: about 30x70x130mm. Package Includes: Style A:1 x Refractometer1 x FlashlightStyle B:1 x Refractometer1 x Refracting oil