Fine crystal glassware is very delicate, and one wrong move can cause the glass to chip. Besides trying to fill in the broken areas, you will also need to smooth out the sharp glass edges. Using a diamond file is one of the best methods for fixing the broken glass, since diamonds are harder than glass and do not scratch.
Dip the diamond tip of the file into water to moisten it. Hold it by the vinyl handle at all times during the repair.
Use the flat side of the file to smooth out the rough, sharp edges at the site where the glass has chipped. File back and forth until smooth.
Use the rounded side of the file to even out the broken area, removing any dips and unevenness.