Speckles and uneven colour — wetting, dispersion or stabilization?

Usually all three, in that order. Work through them in sequence instead of adding dispersant and hoping.

Wetting comes first. Pigment has a large surface area and adsorbs air, so tipping it dry into a liquid gives powder-wrapped air pockets that no amount of later shear will open. Wet it into a paste with a small amount of compatible oil or carrier first, then dilute. A treated grade — AS or SI — wets markedly better and often solves this step on its own.

Dispersion next. Agglomerates need real shear to break, but too much shear fractures particles and shifts hue. Liquids go through a three-roll mill or bead mill; powders through high-shear mixing and screening. Judge by fineness of grind or a microscope slide, not by whether the colour looks even.

Stabilisation last: keep it from re-agglomerating with a dispersant or a higher yield value, and include freeze-thaw in the stability work because temperature cycling accelerates it. For a pressed powder with speckles, check blend uniformity as well — a pigment with a very different density from the base stratifies in the blender, so build the colour up by serial dilution.