Please view these two videos by ToyTimeTim to find your answer! Pyrex glass safety and Borosilicate glass test

I can't imagine a solid glass toy breaking during use. If it did, I imagine there'd be way more trouble than a broken toy (because that much force would mean YOU broke before it did).

They're way more substantial than like, a windowpane or bowl or bottle.

I've never had a glass toy break, and I am extremely rough on the two that I have.

I think they're pretty unlikely to break unless dropped on a hard surface from some great height.

Glass sex toys, assuming they haven't sustained any damage (in which case you shouldn't be using them anyway), are nigh-impossible to break using just your hands. The vagina and anus aren't strong enough to even come close.

Just be careful not to drop a glass toy on a hard surface (though some can survive this without damage), and always check for scratches and fractures before use, and you should be fine.

Love those videos by ToyTimeTim! As long as you've got a quality, well designed toy (no disproportionately thin necks), don't worry about it breaking during use.

The most likely breaking scenarios happen during cleaning (slips and falls on to tile floor) or travel (breaks in suitcase). Both are very unlikely, but if it's gonna happen, chances are it will be one of those.

I have to echo everybody else in saying that unless the toy was damaged to begin with, you shouldn't have a problem with it breaking.