My favorite was a sort of streaky mottled black, that had the highest absolute sharpness. If someone up there could reliably pull that out of the ground and it be in the ballpark of that one hone they could probably corner the modern production natural finisher market if the price weren't exorbitant. Purple gave the most balanced for me, green the smoothest. I had another really good black but not streaked that I traded to nelson years ago. Vt slate is really variable in hardness and consistency so what I say may not apply to everyone. All the hones I have were hand picked from material by the owner once I told him all the parameters I required for them to be good hones.