The invention relates to a method for producing an aqueous suspension of pure-phase .beta.-copper phtalocyanine blue pigment using an agitator ball mill. According to said method: a) in a preparatory step, a phthalocyanine crude blue is suspended by means of a dissolver in an aqueous medium, said aqueous medium containing in particular lipophilic substances, which are similar to binding agents and are compatible with the final application medium and crystalline-phase controlling and/or pigment-surface conditioning compounds; b) said aqueous suspension of the phthalocyanine crude blue is ground in an agitator ball mill to form a suspension of a .beta.-phtalocyanine blue pigment. The aqueous suspension thus obtained is characterized in that it contains a high-grade .beta.-phtalocyanine blue pigment for producing a conditioned .beta.-phtalocyanine blue pigment. The advantage is that said suspension can also be directly converted into a colour concentrate, in particular by means of a flushing and kneading method.