OK its just a shard but my mind says crier. A guy I know keeps telling me insulator. I think NO WAY. Someone here will surely know of this odd neck thick bottle. Any info is greatly appreciated for my brain bank.
I think you're absolutely right. That's not a pole line insulator.
I suppose there's a slim, outside chance it's some sort of unknown capacitor bushing or some such, but I think AntiqueMeds' photo is on the right track.
Thanks guys. Upon further look into decanters. I see that some older pontil era decanters have these same cruder rings. Most have a flared and thin top lip though. Ii has a ware ring of a slightly larger thing on the lip. So could be some sort of stopper ware. the inside of the lip is absolutely smooth though. It has a little concaveness inside but smooth.