Hi kwackers,
my very thoughts about the subject, I´ve used diamond grinding paste, and it works really well... (as abrasive, not as lubricant).
The NanoTube site doesn´t actually claim that the diamond particles will act like small ball bearings, instead they offer this as the "mechanism" to lower friction:
" Originally we thought the nanometer particles provided roller action, however an updated mode of operation is to the right. Whatever the exact means, the results are extended part life, reduced friction and enhanced thermal management."
" Friction transfers our novel Non-Detonation NanoDiamond tm from the carrier oil to the friction surface. The .1nm to 4nm particles embed into the upper regions of the friction surface - providing a coating similar to Diamond Like Carbon film, keeping those surfaces from touching, while reducing friction and preventing wear. Van der Whals attraction allows these small particles to stick to applied surfaces - even after the carrier oil has been removed."
Van der Whals I believe should be Van der Waals...
AFAIK, diamond and graphite have different molecular structures, graphite being "flat"(tish) molecular rings (as in benzene), diamond being tetrahedral crystals...

Whatever. I ordered a small sample from the site ("Treats about 90 Fishing Reels"). If it works up to the hype, great. If not, I´ll give the rest to SWMBO, saying there´s trillions of diamonds in there...

$15 for the advancement of science...
And yes, I got the link from Jan Ridders´s page. I don´t think he would have put it there without even trying the product, and without being reasonably satisfied (but I might be wrong in those assumptions...).