From the site FAQ:
Q: What are the Pendant and Pocket Protection Device stones made of?
A: The stones are made of the same proprietary material that is used to protect computer CPUs.
Hmm, since I make computers, phones and other consumer devices with CPUs for a living I had to think about this. For a second or two.
There is such thing as EMI absorber material. It's kind of expensive so it doesn't get used much in lieu of conventional metal shield cans. Things like the Apple Watch are encapsulated in epoxy and then covered with a thin metal coating in the same fashion as the mirrored coatings on skyscraper glass. This has to be done in a vacuum. Which resembles the folks who fall for this.
