Krishna/Rama/Shiva are denoted in a bluish tinge as the color is to denote serenity and the color of the sky which is considered the ‘heavens’ when death is denoted the soul is normally showed as travelling upward never downward into the bowels of the earth. Hence sky is ‘heavenly’ and the color blue synonymous with calm and embracing.
The color of the throat of Shiva is dark blue due to the parable where he consumes the poison ‘halahala’ which emanated from the churning of the milky ocean by the demons and the God’s using a serpent. This poison would have destroyed the entire earth had it spread through the world and hence Shiva spontaneously swallowed it to prevent the calamity. But his spouse held the throat in her acknowledge to stop it from destroying her ‘beloved’ which therefore remained in the throat turning the ‘Almighty’s’ throat blue Neelakanta.
Sanatana Dharma which is the basis for faith of the Hindus respects everything about nature. Green is fresh and life, red is bright and specific, yellow is calming and knowledge whereas white is pure and satisfying. Blue is heavenly and vast enveloping the entire Universe. Now we have western specialists to advice us on color therapy and balancing our moods based on color. Hindus knew this thousand of years ago.