dichroscope video

The dichroscope is a pocket-sized tool that can aid in the identification of gemstones. This tool is used to inspect pleochroism color in gemstones and to quickly separate some common stones from each other (such as ruby versus red garnet).

The calcite dichroscope is the preferred type of dichroscope used in gemology. It works because the calcite rhomb (Iceland spar) separates the polarized slow and fast ray emerging from the gemstone. If you look at the viewing end of the dichroscope, two small windows are seen.

http://mao.tradegrowthhub.com/test/gemtestinginstruments.com/sale-13918468-gemstone-identifier-jewelry-calcite-dichroscope-with-larger-viewer-and-clear-lens.html