Not sure if this works but i used card board to remove scratches from a watch face, the fibers in card have a slight abrasion and if you cut a sharp flat edge gently rub back and forth with the flat edge. it may take thirty minutes but on a good watch its worth the effort.
I have no idea if this will work on the lumia and this is just a suggestion, gorilla glass on the phone, regular glass on a watch, if you try its up to you but i had great success with my watch, what do you have to lose?