Cargille's Gem Refractometer Liquid has a refractive index of nD = 1.810, the highest of any liquid not containing arsenic. As the name implies, it is widely used with gem refractometers as a contact medium for the identification of gemstones. This light yellow liquid can also be used to reduce or eliminate glare from a gem's surface, facilitating inspection of the gem's interior for inclusions.
This liquid is supplied in an amber glass bottle. The cap has a glass applicator rod attached to it on the inside, designed to deliver a small droplet.
To ensure the liquids maximum shelf life, users should keep this liquid tightly sealed after opening, store it away from direct light and in moderate temperatures.