I don't know about that either, but in some old manuals of Chinese Painting
(written when most artists still had to prepare their own color materials),
there is some description about some colors which shouldn't be ground too
fine because it would lose its brilliance.
In other words, there isn't an easy way as to determine a desired pigment
particle size and then grind all colors to that size. Some colors just can't
be ground to that size before losing its characteristic.