The difference in mass density  between the colloidal particles of mass density  and the medium of suspension of mass density , and the diameter of the particles, have an influence on the value of . As an example, consider a colloidal suspension of polyethylene particles in water, and three different values for the diameter of the particles: 0.1 μm, 1 μm and 10 μm. The volume of a colloidal particles can be calculated using the volume of a sphere .
 is the mass density of polyethylene, which is approximately on average 920 kg/m  and  is the mass density of water, which is approximately 1000 kg/m at room temperature (293K). Therefore  is -80 kg/m.
Generally,  decreases with . For the 0.1 μm diameter particle,  is larger than the diameter, and the particles will be able to diffuse. For the 10 μm diameter particle,  is much smaller than the diameter. As  is negative the particles will cream, and the substance will no longer be a colloidal suspension.
In this example, the difference is mass density  is relatively small. Consider a colloid with particles much denser than polyethylene, for example silicon with a mass density of approximately 2330 kg/m. If these particles are suspended in water,  will be 1330 kg/m.  will decrease as  increases. For example, if the particles had a diameter of 10 μm the sedimentation length would be 5.92×10 μm, one order of magnitude smaller than for polyethylene particles. Also, because the particles are more dense than water, is positive and the particles will sediment.