Have been examining the topic a bit deeper.
The “Ion Tester 3010” costs up to 2000 dollars. What ever it is supposed to test, its construction looks like a geiger counter, yet manufacturer denied it can be used that way.
For the source of the radioactivity in those pedants, there are two possibilities.
a) Natural occurrence of uranium oxide in volcanic rocks.
b) Contamination from Fukushima powerplant.
You might know that in the reactors, water used as a coolant, dissolved into hydrogen and oxygen due to high pressure, temperature and thermal isolation. One of the reactors exploded as a result.
Following video proves that the pendants dont emit just harmless alpha particles:
Apparenlty there are multiple variations of the pedants on the market.
“Original” Japan ones seems to be the most radioactive, emitting gamma rays up to 9000 CPM. Usually are “graded” at 1500, 3000, 4500, 7000 or more CPM, while its assumed “the more the better”.
“Fake” but still seemingly volcanic pedants emit mostly alpha particles and are sub 500 CPM.
Those were mostly manufactured outside Japan in south-eastern Asia.