[hllywd]

The polarized filter method works best with two lenses (I use two camera filters, they work better because they are not tinted like sunglasses), one on each side of the glass. Rotate them to block most of the light shining through and move them simulataneously around the glass. If you see light and dark areas in the pane its tempered. You can try this on the side window of a car as it will definately be tempered.

I wear polarized sunglasses all the time and just "looking" at the glass with them on is not a reliable method to tell if it's tempered or not. The way I describe above is.

Tim