I've had the trouble of cracked glass in the past, although the glass I'm refering to was window panes.
At the end of replacing the glass, on either the last glazier point being installed or the wrong pressure of putting in the caulking, the new glass cracked. Not wanting to replace the whole pane a second time, I ran down the crack with liquid "Krazy Glue" (not Gel) slowly to fill the crack. Doing this in such a manner allows for the LIQUID to penetrate the crack. After done the crack is barely noticeable. Just take a small razor blade to scrape off the exess from the surface of the glass.
