Particle size is not a determinant of whether or not a solution is a colloidal solution. There are colloidal silver solutions which consist of particles that are 0.65 nm in size - which, as I posted before, is slightly larger than two silver atoms and as such is not likely to be larger than a "covalent" particle that consists of one silver atom bonded to three oxygen atoms.
I will agree that there is a likelihood that the results that Chiro did or did not see were related to particle size, PPM and type of particle.