Real Shungite conducts electricity and that is a very rare quality for stones. To check the authenticity of Karelisch Shungiet, you can use it to connect to a battery, two threads and a light.
A practical way for this is the flashlight test: Loosen the back of the flashlight, press Shungite against the battery and the spring. The Shungite will guide the energy and switch on the flashlight

Shungite can also be tested with a multimeter.

Shungite has a very low resistance and the use of a low range gives the result with the highest resolution. For most meters this is 200 Ohm. If you set the range too high, the resolution of the measurement will be low and the result will always be zero.