RIDDLE ME THIS???

I can be found as a shade of round. I can be picked up, but never dropped naked (there used to be three of me, but now there are just two). I am a view on life itself, and all it contains. I can be stepped on, spit on, dripped on and will still look the same tomorrow. It's not so much what I am, but who I appear to be. For I lack the very thing that some people are blind to....