as an experiment, i bought a shungite necklace. coz i actually think i'm sensitive & overexposed to emf (electric and magnetic fields) signals. plus, i sleep on the room where the router is, and an electrical transformer located just outside the window.
it was a gamble, i didn't know if the seller was legit, but i tested with a multimeter, it has zero resistance, so it's real. i don't have an emf meter though, so i'm just going by feeling by saying it has an effect, and i slept better too.
what it's suppose to do ...
Soothe insomnia.
Relieve pain and inflammation.
Heal ailments.
Improve energy levels.
Detoxify the mind, body, and spirit.
Protect against electromagnetic frequency.
Relieve stress and anxiety.
Purify water.
...