has anyone else tried Lloyd Walkers latest tweak

Lloyd Walker has a new tweak: the black diamond crystal for cartridges. It's a crystal you put on either the tonearm or the cartridge that [I KID YOU NOT] transforms the sound!
I know, I know, [don't ask me to explain it,I can't] it can't be all that, but i'm tellin you try this thing [if you don't like it you can return it] for less than half the price of a really good cartridge you get A REALLY GOOD CARTRIDGE!!!
Please post your experience
Right and it's human nature to expect an improvement when spending money on fantasies such as this. IOW, you're hearing what you want to hear.
Lewm wrote,

"I don't say it can't be true, but there must be some support for it in peer-reviewed scientific literature, if it is true. I can find none. Or are you also saying that science has nothing to offer in these matters?"

I suspect audio applications of crystals has not been peer reviewed. Any more than Mpingo discs, Schumann frequency generators, Shakti Stones, the Tice Clock, holographic foil, WA Quantum Chips, tiny bowl acoustic resonators, coloring CDs, and a bunch of other things have been peer reviewed. I suspect two reasons crystals haven't been peer reviewed are the science community is unaware of this application of crystals AND if they are aware of it they might be just a tiny bit apprehensive about tacking such a subject, if you know what I mean. If you think some organization such as AES is going to run out and sign up to look into crystals any time soon, I wouldn't hold my breath.
I put the post out to see if anyone else WHO HAD ACTUALLY TRIED THE THING heard what I did and it seems one other person has had a similar EXPERIENCE.
As I have repeatedly said skepticism [particularly in this case] is a good thing, but to dismiss, out of hand, with NO experience is nether helpful OR scientific. Again first observe then speculate.
Perditty, I meant no slur. Sorry.

Geoff, There has been a LOT of published science on the behavior of crystals in electronic applications. It's actually quite an interesting history dating back to the 1920s. By WWII, quartz crystals were already being used in the defense industry in electronics, and since the method for growing such crystals in a lab had not yet been developed, natural quartz was highly prized and sought after. There is no occult force in commercial audio that could or would suppress research into this area or any other area of science. You greatly exaggerate the power of the industry, and/or you don't quite understand how basic research comes to be done. I have to think that if free (meaning "not in-circuit") quartz crystals (or any of many other kinds of crystals now available) could absorb RFI, there would be a published paper describing this phenomenon. On the other hand, I agree that my failure to find the papers (so far) is no proof that such work has not been done. I will keep looking. There are EEs lurking here. Perhaps one of them knows.
What works in one system may very well not work in another. Stereo systems benefit from tweeking to eliminate resonances, and correct faults. That's what the joy of this hobby is....enjoy.