Interlayer and outerlayer cations have a major effect on the colloidal stability of clay minerals which ultimately determines the colloid's structural characteristics. These colloids exhibit fractal properties that can be used to provide a more detailed insight into their architecture. The effect of different exchange cations (Na+, K+, a Mg2+, and Ca2+) on the fractal properties of different colloidal clay mineral particles (montmorillonite, illite and kaolinite) were studied using laser light scattering. It was observed that the fractal dimension increases as the cation ionic radius decreases. The fractal dimension of the particles was determined at varying pH and ionic strength. With an increase in the pH and ionic strength there is a decrease in fractal dimension. These findings suggest that the presence of the exchange cations determines the compactness of the clay aggregates.