The dual light polariscope, item number 26-2603, will help you identify double refracting stones and distinguish between many genuine gemstones and their simulants.  It has transmitted illumination for the polariscope and side illumination that can be used as a light source for refractometers. It's a complete system which includes a conoscope, AC adapter, and convenient carrying case designed with compartments for storage.  And remember our tools tech team is here to answer any tools related questions you might have.  You can reach them an extension 4300.