... /Tester Refractoscope, Gemmological instrument, Gemology Tool , Gemological instrument Gemological Gem/Gemstone Refractometer/TesterRefractoscope, Gemmological instrument,Gemology Tool ,Gemological instrument-----------------------------------------------------------------Gem Tester ... : Refractive Index: 0.01 Size: 30× 70× 130mm Gemological Gem/Gemstone Refractometer/Tester