【Precise Measurement】 Utilizing the principle of total internal reflection and equipped with a high-precision sensor, the measurement range covers 1.300-3.000, with a measurement error of ±0.005 and an accuracy of up to 0.001. It can acquire gemstone optical data non-destructively, providing scientific and reliable quantitative support for jewelry identification. 【Easy Operation】 Say goodbye to the cumbersome steps of using refractive oil with traditional refractometers. Simply place the polished gemstone against the measurement platform to quickly determine its crystal structure. With 1.487 and 1.806 calibration blocks, pre-measurement calibration is even more convenient. 【Clear Readings, Long Battery Life】 Equipped with a large backlit LCD screen, data can be clearly read even in low-light environments. The built-in 700mAh rechargeable lithium battery supports up to 10,000 measurements on a single charge. The digital gemstone refractometer provides stable output whether in the laboratory, jewelry store, or field for identification. 【Working Principle】The working principle of the refractometer is based on total internal reflection. The refractive index is a very important optical parameter, and the characteristics of gemstones can be determined based on this parameter. 【Wide Range of Applications】Quickly and accurately identify single and double gemstones, diamond colored gemstones, designed for measuring the refractive index of gemstones and solid materials.