Automatic Dental Handpiece Lubricator with Time Scale Display - Efficient Maintenance & Cleaning System

RHG 1.30-1.81 Gemstone Refractometer Jewelry Emerald Zircon Testing Tool With LED Flashlight Double Refractometer Professional\n\nNote: The refractive index of diamond is 2.417, so it cannot be measured.\n\nGem refractometer is the most important tool for measuring gems. It can measure the refractive index of gems nondestructive, quickly and accurately, and determine other optical characteristics of gems.\n\nThis product uses high refractive index lead glass as the test prism;\n\nMeasuring range: 1.30-1.81,\n\nAccuracy: \u00B1 0.002,\n\nPower supply device: LED light with AA battery;\n\nEquipped with 3ml refractive oil (refractive index 1.78)