LED light and audio result indication. Red light will be displayed and audio indicator sounds if the stone is a real diamond. Simple calibration for stones of different sizes. Accurate and reliable reading. Lightweight, matched with a convenient carrying case. Detailed user manual included in the package. The thermal conductivity meter is designed and manufactured according to the thermal conductivity of diamond. It is specially used to identify real and fake diamond. Tips: Gemstones should be clean, dry, and at room temperature. During the test, place on the first or second grid. V2 Gold Test Kit with Gemstone Pen, Handheld Electronic Diamond Tester with LED for Diamonds, Sapphires, Rubies, Crystal, Agate, Jade, Gems, Hardness Testing Tool Features: Easy to use. LED light and audio result indication. Red light displays and audio indicator sounds if the stone is a real diamond. Simple calibration for stones of different sizes. Precise and reliable reading. Corresponds to a test platform for loose stones. Lightweight, matched with a convenient carrying case. A detailed user manual is included in the package. Color: black. Power supply: 1 DC 9 V battery (not included). Dimensions: 16 x 4 x 2.2 cm. Maintenance and repair: 1. The instrument is very sensitive to the probe; handle with care and store in the sheath when not in use. 2. If the indicator light appears dim, the battery is low and should be replaced promptly. 3. Remove the battery if the instrument is not used for an extended period. 4. For accurate performance, annual calibration is recommended. Additional information: 1. The thermal conductivity meter is designed based on the thermal conductivity properties of diamond and is intended for diamond verification. 2. This device is a precision electronic instrument; use in environments between 5–35 degrees Celsius with relative humidity under 80%. 3. Ensure gemstones are clean, dry, and at room temperature before testing. 4. During testing, place the stone on the first or second grid. Package includes: 1 Diamond Tester