I've had these glasses for twenty years - a dozen each of three sizes. Raised kids with them and no one ever broke one. 'Til last night.
It was pretty impressive. I dropped one on the slate floor and it shattered - kind of like safety glass - into lots of small pieces. The pieces scattered from one side of the room to the other. I imagine I'll be finding more pieces over the next few days. Luckily they aren't very sharp.