【GEMSTONE TESTER】This diamond testing instrument uses the principle of thermal conductivity to identify and distinguish between diamonds and moissanites. Advanced electronic tester designed for quick and accurate identification of diamonds and various gemstones, it can differentiate between 16 types of gemstones. 【RETRACTABLE PROBE】Retractable probe's thermoelectric probe ensures that the pressure between the probe and the gemstone remains constant. The probe (0.6mm) can be used to detect diamonds as small as 0.02 carats. 【ACCURATE DATA】Professional diamond test pen comes with a metal alarm buzzer to ensure that the probe remains in contact with the gemstone during the test. Consistent and reliable test results can be obtained every time, without waiting, and it is easy to use. 【ASSISTED THERMAL CALIBRATION】Built-in plug-in glass and calibration (CAL) test disk, you can easily calibrate your device yourself according to the test environment. Note: Calibration may be affected during transportation. If you encounter problems, please contact me. 【APPLICATION RANGE】Used to test and measure diamonds and gemstones, reliable testing device is suitable for the jewelry industry, educational institutions, laboratories, jewelry manufacturers, diamond certification companies, jewellers, gemologists, and precious stone dealers for quick authenticity verification.