Perfect for cost conscious Gem Assayers! 1.800 Refractive Index allows you to use your Gem Refractometer to a very wide range. 1.81 Gem Refractive Index Fluid is better, but WAY more expensive! American Made! These products are made by a NIST certified lab. The other stuff on Amazon is sourced from where exactly? Labeled Bottles. Believe it or not, some Sellers do not supply a label! This Vial contains 1.8ml - 10+Grams of fluid - (Half Full Bottle in a 4.0ml Vial). Applicator rod is in cap for easy transfer of product. Additional Details ------------------------------ Package quantity: 1