2Pcs Diamond Tester II & Moissanite Selector Gemstone Jewelry Gems Tool LED Audio Kit Easy to use even for a new beginnerDiamond indicator will be showed if the stone is a REAL diamond (Green light) Emit audible sounds to give accurate readingMetal alert (continuous buzzing sound when user accidentally touches metal rather than stone) LCD display & LED indicatorLarge / small switch for testing diamonds +/ - 8 points,To emit sounds to give accurate reading Dimension: 16.5 x 4.2 x 2.2cm Appearance size: 160*40*21mm If stone is Fake crystal, a simulant such as cubic zirconium ( CZ ), will be no reaction