You know argyria, the blue-gray skin people get from taking a lot of colloidal silver for a long time ...  So their skin slowly changes color, and they don't notice because they see the image in the mirror according to their memory of themselves, until one day, they notice, they're blue!

I wonder if this is why the Hindu gods are blue.  Colloidal silver is an antibiotic, and perhaps the ancestral royalty had the money to use a lot of it.  Maybe they were blue, and after many years, stories of them turned into the Hindu religion.