Portable Diamond / Gem Tester 'Diamond Selector V2' with Case and Gemstone Platform Jeweler tool.
It's a very intuitive easy to use device, you scroll the wheel (manual says how much; there is also a handy table on one side of the device as a reminder), touch the stone on a straight angle and wait for BEEP-BEEP-BEEP))) and light to go into red spectre. Buzzing sound means you touching the metal.
Used, in perfect working order, sold as is.
You need a battery 9v (kind of rectangle shape wider than AA). Mine just died on me.
The battery compartment is in the bottom, slide it open and you will find a plug for the battery, it shows plus and minus, hard to do is wrong, don't pull the plug too strong, it's soldered by 2 wires. Put the battery in, slide it closed, start checking your grandmother's diamonds)))).