Here's a link to some AH-1W optics. Different shapes, obviously, but the colors of glass should be similar. The left window is for the FLIR, and is basically black-colored glass. Since all FLIR cameras operate on the same principles, the color of the glass would (should) be the same for other aircraft. The window on the right is for DVO and CCDTV. That pane is transparent, but depending on the angle, can have a purple or bluish tint to it. Hope this helps.
http://www.popasmoke.com/visions-iraq/image.php?source=76