Taking into account the importance of characterisation of stability of dispersed systems in both fundamental research and industrial technology, three optical techniques, were used and compared to study sedimentation behaviours of mineral suspensions. The agglomeration and dispersion phenomena of mineral suspensions in water and ethanol media, has been studied by a granulometric and sedimentation approach (electrophoresis mobility, particle size distribution, clarifying speed, sediment formation). So, this experimental work has perfectly shown the necessity to achieve a complementary approach by these three optical methods to completely investigate the sedimentation behaviours.