With expecting the optical quantum-dot fabrication of organic dyes and pigments, we tried the refinement of Cu-Phthalocyanine particles by nozzle-jet water cavitation method. Commercially available Phthalocyanine powders are known with deep blue to green colors. However, the color is known to be bright if the pigment size becomes small and mono-disperse. The nozzle-jet water cavitation method for the refinement is to break the aggregated particles on the points where they adhere by the shock wave that is generated by the collapse of non-equilibrium cavities created in a fluid. The heat that is created at the collapse of cavities may reach several thousands degree, for several micro- or pico seconds, but the energy is small and not effective for the refinement. The Phthalocyanine powder was injected with water and surfactant to prevent the re-coagulation. The single open orifice (0.12mmφ) was used and the injection pressure was up to 1500kgf/cm². The mean particle size after cavitation was 35 nm and the minimum, 20nm.