Maybe not.

One of the things I'd love to be able to do with lampwork is add creatures and other embellishments to practical objects. I have a strange desire to put eyeballs at the bottom of mugs and since you can get hold of pyrex mugs, I decided to give this one a go over the weekend. In theory, pyrex is borosilicate glass (at least if it is old enough - the company was bought several years ago and is now more of a brand name than a description of the glass used).
I bought a very cheap second-hand white pyrex mug, bunged it in the kiln to heat up and, while I was waiting, made the eyeball.
I love making eyeballs. The eyes give so much expression. This one was human not reptile and involved layering and pulling thin strings of slightly reflective blue/green glass over a base of black to form an iris. Push a thin dot of black into the centre at the end to make a pupil and add a clear lens. Done properly, it is quite realistic.
Eyeball made, I carefully retrieved the hot mug from the kiln with tongs and took it over to the bench. Stuck it in the flame, heated up the base... so far, so good. No cracking with the torch heat. It was an awkward angle but I got the eyeball into position, started to heat both mug and eye. All went well until I reached for a tool to just push the eyeball in a little further and stick it properly to the mug. One quick push and bang, glass shards all over the worktop and from among them, glaring balefully upwards, a furious eyeball.