Jeweler's Diamond Testing Pieces-Professional Loupe and Electronic Diamond Tester Machine
Can distinguish diamond from white corundum and YAG.  Effective in distinguishing between real and fake diamonds.  Very easy to use.  LCD display.  LED lights.  Emits audible sounds to give accurate reading.  Buzzer alerts you when the probe tip touches metal.  Diamond indicator illuminates (GREEN) to report that a REAL diamond is being tested.  If stone is fake, such as a simulant cubic zirconium (CZ) crystal, there will be no reaction.  Instructions included.  Great tool when shopping for jewelry, buying/trading diamonds, collecting gems, gem stone bead work, scrap jewelry collecting, bidding at auctions, estate sales & more.