My Dremal tool Kit has several small types of fine grinding stones - different shapes - which I use to smooth-out/eliminate glass scratches and chipped edges. I finish-up with polishing compound. Although it somewhat thins-out the glass at the repair area, if carefully and patiently done, the repaired area is not visable to the naked eye. I have used this procedure on fine glassware.
If you have access to a Dremal Kit practice on a scrached item and see if it works for you. Dan