Relevant topic analysis on Glass dildo:

Silicone or Glass for anal toys?
Do you prefer the feel of silicone or of glass?

Do you use glass dildos for orgasms?
I'm new to the idea of glass and wondering how often orgasms are experienced with them. do you use glass dildos for ograsms?

What makes glass so awesome?
I've heard a lot of people talk about glass dildos and how they're fantastic. Can anyone tell me what they like about them, or don't like about them?.

How do you like glass vibrators?
Do you like glass vibrators? better/worse/just different than other materials? what's your favourite material?

Cherry dichro glass dildo with spiral ribs – glass dildo
is glass safe

There are different types of glass, but as long as you handle and store them properly, they are one of the safest and most favoured materials on the market.

Here you can find the same discussion going on.
Here, ToyTimeTim demonstrates the durability of Pyrex glass. It's really interesting to watch, especially if you are quite skeptical of glass.

Glass sex toys are extremely strong, and impossible to break using just your hands, so a person's vaginal or anal muscles certainly aren't going to do the job. The only thing to be concerned about is storage and not dropping the toy on a hard surface (though some glass toys are even strong enough to withstand being slammed against concrete).

While I've never tried a glass toy, I would really like to.
As previously mentioned, they are generally tempered and treated to be particularly strong, and won't break with typical and judicious use.

The biggest precautions are to be gentle during use, as rigid materials can injure you more than soft ones if you are rough... And to check the surface of the toy for cracks or chips before use. Otherwise, they're very safe. I hope to invest quite soon, myself.

Thanks for the info everyone!

Tempered borosilicate glass is very strong and resistant to temperature changes. As long as it isn't scratched and it's been made properly there won't be any problems. Scratches concentrate force, so a scratched toy needs to be treated with care (small scratches can be buffed out).

Be careful with temperature on glass and metal plugs because they have a pretty big thermal mass, and you can injure yourself if the plug is too hot or cold.