There was a long winded discussion on the AACA forum about polishing glass. A couple of guys that worked in the glass industry chimed in. The general consensus was that you can shine it up a little but as far as polishing scratches anything over the slightest mark will be almost impossible to do. B-Hill is correct, if you can catch a fingernail on it, chances are its too far gone. I talked to my glass guy several years ago and he told me the same, also if you do polish you want to keep the heat to a minimum.