Can't remember where I read it, the polarizer filter is not on the surface. Not sure if the N9 glass has other coatings on top.

Edit:

Did a search ... it was on the Lumia 800, so I guess it would apply to the N9 as well.

"The Corning Gorilla glass makes sure the display won't get scratched either. Under that tough cover hides a polarizing filter that reduces reflections and improves the image quality."

http://www.gsmarena.com/nokia_lumia_...view-686p2.php

Ok, more info from Nokia Conversations:

"In ClearBlack Display phones, the polarizer is placed between the window and the touch sensor. The goal of this layers is to stack the optical performance with an air-gap solution. By putting the polarizer between the touch and display, engineers can block reflection from the captive sensor grid. To envision this, tilt a traditional touch screen phone in direct sunlight…see the grid of tiny dots? That’s the capacitive sensor grid."

http://conversations.nokia.com/2011/...ifferentiator/