Duo gem tester (Presidium PDT-II) Options_For the partially sighted Orange backlist display

Orange backlist display

Four AAA batteries (supplied)

diamond is singly refractive

this is particularly powerful) but also good for stamps and coins

Duo gem tester (Presidium PDT-II) Options_For the partially sighted Orange backlist displaySummary Bench model. A dual tester with both thermal meter and reflectivity meter. Place the probe on the stone to operate analogue meter (the thermal meter, see detail in the extra pictures). Place the stone over the sensor (even if it's in jewellery) to operate the digital meter (the reflectivity meter). You don't have to use both systems, you can choose one or the other. Includes heavy duty nylon carrying case and a PP3 battery. Also a power supply