Krishna is actually bluish black.There is nothing particularly symbolic
about it, although in Vedic culture the color blue is considered the
color of beauty and love, youth and supreme attractiveness.Krishna, as
the Supreme Person, is completely independent and can choose to
appear in any color He chooses. He has chosen to be the color of beauty
tinged with the hue of blue clouds.Also Krishna's colour is not matched with the material colors we consider as bluish black but it is completely transcendental and beyond our sense perception.
In one line answer , Krishna is bluish black simply because he wants to be.
In one line answer , Krishna is bluish black simply because he wants to be.