The best way to remove scratches from any glass is using a 600 grid wet/dry sandpaper untill the scratch is gone. Use it will the sandpaper is wet. Then follow with at least an 1000 grit sandpaper while wet to buff out the blurr that'll occur from you leveling out and removing the scratch. Then follow by the 3M rubbing compound (it's the equivalent of a 1500 grid wet sandpaper).
I have resurfaced my watch faces many a times this way when it get all scratched up... Terrible on watches.
