My favorite color is blue. I love it because it is  between violet and green on the spectrum of visible light.
Blue is a great colour. I consider to also be one of my favourites. Is it a prime colour?
Most time blue contains a slight mixture of other colors; azure contains some green, while ultramarine contains some violet.
That is amazing but is it one of the prime colours?
Maybe, the  clear daytime sky and the deep sea appear blue because of an optical effect that is called  Rayleigh scattering