Why are solar cells blue and not black?

Blue are Multi crystalline (Impurity Added) while black are Mono Crystalline( Pure form)

If the solar cells absorbed all incoming visible light, then they would simply appear black. However, no solar cell is one hundred percent efficient in absorbing all visible light, It is this weak reflection that gives rise to the effective blue color of common solar cell panels, so the anti-reflection technology used now normally absorb light, letting blue lights reflected most. The most efficient solar panel should be black, absorbing nearly all the light.