Actual color of colloids
Colloidal solutions scatter light of different wavelenghts in different directions, and that's also dependent on the size(!) of the colloidal particles.
To see any scattering at all, there only has to be a difference in the refractive index of pure solution and dissolved particles.
The individual colour (i.e. absorption spectrum) of the particles is irrelevant to the scattering, but of course it additionally changes the colour that you see. Absorbed light does not get scattered, obviously.