Hi David, I know this is a rather old thread, but Frank has just ressurected my latent interest in Ã‡eşm-i BÃ¼lbÃ¼l glass, and I really think this piece isn't.
This type of Turkish glass is extremely fine and thin, and in all the pieces I have ever seen, none were this thick or so crudely finished.
If you put Ã‡eşm-i BÃ¼lbÃ¼l (copy & paste so you get all the accents!!) into the search engine, and click on pictures, you will get some beautiful examples of their glass.
This doesn't tell you who made your flask, and I van't say for certain that it isn't Ã‡eşm-i BÃ¼lbÃ¼l, but I hope this might help a little.