Abstract: Apparatus for classifying particulate material on a particle by particle basis according to the extent to which the particles possess certain attributes, such as the presence of particular colors when viewed from different directions. A particle feeder (12) feeds particles past an inspection system (13) which inspects each particle and derives signals which are a measure of a plurality of attributes of the particle. A separation or airblast mechanism (14) operates to direct particles to multiple outlets (15) according to the signals derived by the inspection system (13). This operation is controlled by a signal processor which can store a plurality of sets of specific values of attributes each set of which is typical of one of a plurality of particular classes into which the particulate material is to be classified and can compare subsequently measured sets of values of attributes of successive particles with the stored sets to determine a closest match with one of the particular classes.