Re: Bad hookah vase, what do you think?
the only way to have gotten that vase that way is to have gotten it hot enough to manipulate the glass (1200-1600*f at least) then cool it down over 12-24 hours from 1000*
as to grinding it you will need a silica based abrasive at the minimum, but diamond works better, the correct tool for it is a flat wheel grinder which other than a professional glass shop you wont find one. if you try to grind it at home you need to have a lot of water flowing over the abrasive. just grinding it wont lead to cracking (polishing with serium may crack it, my glass professor cracked at $40,000 piece of glass at a job he had when he was cold working pieces for some famous glass blowers and he cracked a piece in final polishing, his boss understandably had a shit fit)
honestly i would just use silicone glue or glue something with silicone glue or UV glue to the top that is easier to shape than glass