Refractive Index Liquid =1.80 for Gem Refractometer, Oil, Fluid, Test, Gemstone Perfect for cost conscious Gem Assayers! TWICE as much as our other listing! Comparable to more expensive chemicals, this one is economical. 1.800 Refractive Index allows you to use your Gem Refractometer to a very wide range 1.80 Certified Refractive Index Liquid for Refractometer 1.8ml - 10+Grams - Half Full Bottle in a 4.0ml Vial - Applicator rod in cap for easy transfer of product.