A process for the manufacture of pigments comprising a colored composition incorporated in a polycondensation resin, wherein the reactants for the formation of the polycondensation resin and the colored composition are introduced continuously into an extruder, preferably at a temperature of between 100.degree. C. and 280.degree. C., the mixture is caused to travel forward in the extruder, at the end of reaction the mixture is withdrawn continuously from the extruder, and is deposited continuously onto a conveyor belt, broken up into thermoset flakes, and cooled, the conveyor belt having means for cooling and means for detaching the flakes from the belt. The process is particularly suitable for the preparation of fluorescence pigments. Also disclosed are compositions comprising diketo-pyrrolo-pyrrole colorants and certain polyester or polyamide resins as well as a process for the preparation of the compositions.