Gem Indicator (PGI) Gem Tester Features a color input function that allows users to select from a range of 12 common colors for more accuracy Easy-To-Read clear Digital LED Screen and fast read out Internal Library Database Function of gemstones and their possible colors. Helps indicate up to 31 different types of colored gems Requires three AAA Batteries and has USB connection to PC for more value-added functions Ships from Jeweler's Supermarket