The HMKIS Diamond Tester Pen Selector 2 is a reliable tool for identifying and testing diamonds using a Thermal Conductivity Scale. This pen includes a 60X microscope for added precision and features a sleek black color. Powered by batteries, it offers a measurement accuracy of +/-2% and is suitable for jewelry designers and enthusiasts looking to accurately determine the quality of their diamonds. With its compact size and included magnifier, this diamond tester from HMKIS is a must-have for anyone in the jewelry industry.