Presidium Instruments Gem Tester II (PGT II) Now with Assisted Thermal Calibration (ATC) for Identifying Diamonds/Moissanites and Common Colored Gemstones

Testing

The presidium instrument gemstones tester is a good product. It would have been great if there where actual light to indicate the name of the exact stone instated of just a line with more the one name leaving you to guess what exactly it's.

This is my second Presidium gem tester. It is easy to use, although sometimes the calibration can be tricky. I have found that if you let the unit warm up for at least an hour, it minimizes the need for re-calibration. I use if for my vintage jewelry hobby.

I like the variation this tester has for identifying various gems . However , I find the pen has been extremely finicky and I can hardly have it calibrate up to the Cal indicator level without constantly cleaning and wiping down the cal glass and pen tip. I may have received a faulty pen as it has play back and forth ?

This tester clearly displays hardness of all types of gems in all types of settings. It quickly clears up any mysteries about the gem at hand. Highly recommend!