Are Shakti Stones effective?

I have never used Shakti Stones and wonder if they really work and, if so, what do they do,  I have used the Shakti Holographs and found them to magically focus the sound and tighten the soundstage. From what I have heard, even from Shakti, is that the stones make a significant difference is some usage and less in other. Has anyone used these and what do they do?
Yes they hurt if you throw them at someone. 
The best most experienced dealer I ever met stayed with me one time for a couple weeks when he was moving out here to Washington. He brought a whole van full of gear, and I got to try it all. Among the many tweaks and cables and amps was a Shakti Stone.

I was no stranger to tweaks at this point and real eager to hear what it could do. Tried it all over the place. Straining to hear even the slightest difference. The only place it did anything at all was over the transport section of the CDP. Even there it was barely noticeable.

When I told Stewart I tried it the first thing he said was did it work over the transport? Because that is the only place it did anything. So in one fell swoop I learned yes indeed tweaks are for real, we both had the same experience, and Shakti Stones are a waste of money.

Unless of course you like the looks. They do look better than a phone book, which is the performance level they are competitive at.
In the SMc Audio VRE-1 manual, Steve McCormack has a section devoted to power cords, interconnects and devices that owners might wish to try with his preamp. Among those items are Shakti Stones. 
I don’t know a more skilled audio equipment designer/builder and acute listener than Steve McCormack. 
Some end users may have less issues with RFI/EMI than others. This should be taken in consideration before making a proclamation against any product designed to address those issues.