I'm imagining a ground glass "stopper" (solid 19mm male ground glass piece) sitting on top of a glass jyarz jar. The jar slides into a plastic sleeve and a rubber strap connected to the plastic sleeve goes over the top of the stopper. Or, you just screw a plastic lid on top of the stopper to hold it on, much like the current design only with a stopper sandwiched in there.
Ground glass is very expensive, the very first prototype had ground glass but couldn't make it work cost-wise. I do think there would be demand for really nice ground "artisanal" glass containers...very high end. Beautiful. That's a whole 'nother business.
-JyARman