Nano-sized phthalocyanine pigment particles include a phthalocyanine chromogen structure as the main component, and a substituted soluble metal-phthalocyanine dye as a minor component that is associated non-covalently with the phthalocyanine chromogen structure, wherein the presence of one or more sterically bulky substituents on the substituted soluble metal-phthalocyanine dye limits an extent of pigment particle growth and aggregation, to afford nano-sized pigment particles.