Digital refractometer by Presidium (model Prim II) Digital scales - regular lines - resolution 0.001g a hallmarked item)

a hallmarked item)

Hold the light button to adjust brightness

All about (and reviews of)  binocular (head-worn) magnifiers- especially the surgeons-type

Can be used anywhere

Disadvantages over an optical refractometer:- it's not as versatile as an optical refractometer

Digital refractometer by Presidium (model Prim II) Digital scales - regular lines - resolution 0.001g a hallmarked item)Summary Made by Presidium, the leading manufacturers of gem testing equipment. There is downloadable software to connect it to your computer. The reading is then displayed along with a list of stones that match the reading, and you can click on each stone to see more information (constants). This saves time looking up charts. Comes with a USB cable (connects to any computer mobile device USB mains adaptor). Works with loose stones and also stones