Multi Tester for identification of Diamonds and other Gem Stones. Measures 6.3 x 1.65 x 8.7"Uses 3 AAA batteries or adapter. Will identify diamonds and very small diamonds, Moissantes based on thermal & electrical conductivity properities. A light of either orange, red, yellow, & green indicates results of testing. A beep indicates a diamond. Made by Presidium Instruments PTE. LTD. I have had this a while but never used it.