I had the oppurtunity to test a gemindicator from Presidium and i can say from my experience that it was not reliable. I tested a well known gemstone and it gave different answer 2 of 4 times. The same to the Diamond/Moissanite tester. I tested 2 indian made moissanites and they passed for diamonds.
My opinon of the electronical devices is that they are not reliable. You have to work with the traditional equipment.