That's wild, thanks! I tried with a couple of my pieces (although they do say "not polarimeter safe") and they did have some noticeable brightness gradients, th

That's wild, thanks! I tried with a couple of my pieces (although they do say "not polarimeter safe") and they did have some noticeable brightness gradients, though I hesitate to call them patterns. What DID stand out looked like brown scorch marks or stellar jets/magnetic poles. I don't think they were really scorch marks, but it was striking just how brown that tiny area was. Edit: got a picture but it's more of a red and blue interplay than just brown. http://imgur.com/a/0xRlg9D http://imgur.com/a/0xRlg9D Maybe it's the rgb of the monitor. And I have seen similar colors in windshield polarization. It makes more sense if you rotate the glasses and watch the brown and blue flow through the patterns