Recently I did a reaction in the lab (the reaction itself is not important) whose product was colloidal sulfur. As I watched the sulfur particles form I noticed something strange: At first the sulfur particles appeared white, but after a while the solution turned yellowish (probably when the size of the sulfur particles grew a little). I know that sulfur's colour is yellow by nature, because of its absortion soectrum, and I understand that the white colour is probably due to Mie scattering of light by the colloidal particles.
My question is: Why aren't the particles yellow? if the absortion spectrum has as a consequence a yellow colour I would expect that spectrum to remain valid at all dimensions of the particle, the particle can't just randomly decide to stop absorbing light of some wavelenght when it reaches a threshold size... can it?
I know that Mie scattering predicts that a particle will scatter all wavelenghts equally if its size is comparable or bigger than the wavelenght of light, but I would have thought that if the particle absorbed a specific wavelenght that wouldn't change with size.