To follow up on the "rocket science" line....
Research "Stokes law"...
The rate that a solid settles out of a suspension in a fluid
has well known dynamics. If you avoid "floculation" you can
begin to classify fine grain particles by size.
This is how the old barber hone abrasives were classified.
Today I have been reading that electrostatic fields are used
to the same purpose.
Floculation can be triggered by disolved solids i.e. salts.
After floculation filtration is easier because the clumps are
larger. Floculation does hinder some spray equipment
as the clumps can get large enough to clog the nozzle.
In this case you have diamond dust that has already been classified
so all you have to do is disperse the material well enough to spray
on a surface in a an even uniform way. Dusting the strop using a
small brush is a good trick.