Unique design: professional design, excellent workmanship, accurate and reliable testing, LCD display and LED display.[Easy to use]: The diamond tester is a portable professional electronic testing tool. When the stone is a real diamond, the red light comes on and the audio indicator beeps.Conditions of use: The thermal conductivity meter is an electronic instrument specially designed and manufactured for the thermal conductivity of diamond. It is an electronic precision instrument. The operating environment is 5-35 degrees Celsius. The relative humidity is 80. Test stones must be clean, dry and at room temperature.Versatile usage: This gemstone tester is not only a diamond tester, but also a multi-gemstone tester. It can identify the authenticity of gemstones, including: diamonds, sapphires, rubies, crystals, agates, emeralds and other gemstones of various sizes.[Precautions for use]: No matter what gemstone is tested, the probe and the object to be tested must form a 90 angle. * When testing diamonds, the right index finger must touch the metal plate on the back of the tester, do not touch the panel when testing other gemstones. * Do not test on metal. * Do not wear gloves. * Please use the correct method to avoid mistakes.