About forty years ago I was restoring an Ithaca 'Parlor' model calendar clock that was missing its pendulum. I borrowed one from a friend and spent over eight hours cutting, beveling, etching and polishing this piece of glass to duplicate the original.
When I had used an abrasive blaster to etch the trademark, a corner of the mask folded back leaving a tiny spot that had to be polished out.
During the wet sanding, I was almost finished when it slipped from my hand striking the concrete floor damaging it beyond repair.
I honestly came SO close to crying.
Crestfallen, I no choice but start all over again.
Through the years, and with other items, I have learned that I have developed a foolproof way to determine if a glass object is rare, antique or valuable.
Just let me hold it and if it is valuable I'll break it without even trying.