(Subject line an homage to Larry Niven)
I like the idea of glass teaware. Having spent a number of years in academic and industrial research labs, though, my standards of quality and utility for glassware are somewhat distorted relative to the pots'n'pans market. I do quite like cut (as distinct from molded) crystal from Ireland and Bohemia; there, the many irregularities give voice to the hand-worker's efforts. But I have yet to see a piece of glass tea-brewing equipment that I thought well-designed and -executed, especially as regards glass weight over various parts of the object.
Nonetheless, I keep a few glass pots and gaiwans, mainly to give away and to show newbies what's going on in there. Since hot, strong tea supersaturates on cooling, leaving tough residues, cleaning is an annoyance even with greens and whites.
Now that my main daily tipple is cool-brew shu Pu (and the occasional low-roast fragrant oolong), though, I've been finding a glass gaiwan ideal. With steep times running many minutes to a few hours, a glance across the room gives an immediate gauge of infusion strength. And since nothing is cooling, there are no deposits to clean.
Main feedstock for this is Tuochatea's various Yunxiang bricks, which I think are about the best value going on ripe Pu-erh. That cherry-cola note really comes through on room-temperature brewing. Haven't had such good results with sheng Pu-erhs; good presentation of plum and camphor notes, but flavor balance otherwise not comparable to that achieved with fast, hot steeps.
-DM