A process for the manufacture of deep-shade perylene-3,4,9,10tetracarboxylic acid dianhydride pigments, wherein finely ground crude pigment of which the average primary particle size is from 0.01 to 1 Mu is treated with a primary or tertiary aromatic amine which is liquid at the treatment temperature, or with a strongly polar aprotic solvent, as swelling agent, until the pigment has acquired the optimum color strength. After removal of the swelling agent, a deep-shade, pure pigment is obtained, which is suitable for all pigmentation purposes.