The DiamondNite tests for diamond, versus cubic zirconia or synthetic moissanite, so it is a true dual tester.  We promise you'll be amazed by the accuracy and simplicity of this test.  One touch to the stone - no beep means it is a CZ or other fake, first continuous beep means diamond (green light), if it is followed by a higher continuous beep, then it's a moissanite (red light).   It's that simple to operate.  Uses 9V battery.