The diversity in coloration and even facial markings of Blue Jays is quite remarkable. There aren’t any plumage or size differences between the sexes, nor do they dress up for breeding season like other species. But each individual is slightly unique. I suppose as a communal bird that helps them tell each other apart?
As you may already know, their feathers are not actually blue. The blue we see is the result of light refracting through special structures on the feather barbs. The intensity of the blue is controlled by the amount of melanin, which is actually a brown pigment.
Apparently, Nature does not adhere to the What You See Is What You Get (WYSIWYG) principle.