High Precision: This refractometer is expertly crafted for the swift and accurate identification of single and double refracting gemstones. It features a measurement range of 1.30 to 1.81, allowing gemologists to explore a wide variety of identification options. Compact Design: The lightweight and portable design of the refractometer makes it easy to carry in your pocket or tool bag, ensuring convenience and accessibility wherever you go. Gemstone Identification Tool: This diamond tester efficiently identifies both single and double refracting gemstones, including diamonds, moissanites, and colored gemstones. Reliable Performance: The jewelry refractometer boasts a clear display for effortless reading. With an integrated light source and a user-friendly digital scale, it's suitable for use in various environments. Measurement Instructions: Apply drops of refractive oil to the prism surfaces using a thin glass bar to determine whether a gemstone is uni-axial or biaxial, either photopositive or photonegative.