A gem tester is a device used to identify the type of gemstone being tested. It works by measuring the electrical conductivity of the gemstone, which is determined by the type of mineral it is composed of. Gem testers are available in a variety of models, ranging from simple handheld devices to more sophisticated laboratory-grade instruments.

To identify a gem tester, look for a device with a probe or electrode that is used to make contact with the gemstone. The device should also have a display that shows the results of the test. Some gem testers also have a built-in light source that can be used to illuminate the gemstone for better visibility.

When using a gem tester, it is important to follow the manufacturer’s instructions carefully. This will ensure that the results are accurate and that the gemstone is not damaged during the testing process.