Abstract Particle shape characterization is playing an important role in many current processes and operations. Characterization techniques based on the behavior of particles in an apparatus offer a rapid, simple method for examining large particle samples and have the advantage that they can physically separate the sample into various shape fractions. Operating on the principle that settling velocity is influenced by shape, the continuous classifier or settler takes a closely sized sample of particles of the same density, and separates the sample into various shape fractions. Experimental results have demonstrated that the settler has satisfactory separation and recovery efficiencies and could be used for quality control of shape in an industrial environment.