Are Shakti Stones effective?

They have a patent you can check out that has a diagram of the internals and describes their construction and how they are supposed to work. The stone part is just a shell for the actual internal working components, I don't know what its' purpose is or why they settled on the stone aspect of the shell.
I'm open to try any tweak if the price is right and the resale value is decent in case it does nothing of note. I bought a Shakti Stone, tried it in different spots in different setups both audio and video, it really made a big difference placed on an Extron rgbhv distribution amplifier I use with broadcast monitors. I haven't moved it since to other spots after changing things round and it's been years since I tested things out so I can only say I noticed a real change in this one spot. Find a dealer that may have a demo period if one wishes to try them out for themselves.

I had them for years, used them in different systems and NEVER noticed any difference when they were applied on different components of each setup. I finally sold them a few months ago. 

These stones work best on a Cd player that uses only green magic marker on the edges of the CD's.  However, they are good for throwing at Barry Manalow CD's and LP's.

Whoops!  Spell check got me again.