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The reason pigments or anything else is blue is also because of physics.

While true, it might be worth noting that if you grind iridescent blue material it will loose its color. Pigment will not.

A friend of mine once claimed that the sky wasn't blue. I challenged him, expecting some argument about physics and Rayleigh scattering.

Instead he looked at me and, with a straight face, said "it's the spy satellites which are blue. And there are very many."