... 81, Size: 30x70x130mm. Gem Refractometer CL-181LLGem Tester Refractive index is one of most important optical parameter. Gloss of ... the measured value of refractive index because every kind of gem has its inherent refractive. Besides, index of double refraction ... liquid,manual; one year warrantyMeasuring rangeRefractive Index: 1.30-1.81Resolution Factor:Refractive Index: 0.01Size:30×70×130mmNote: 2ml ...