Blown, probably non lead glass. Polished pontil and applied clear glass ring at neck, beginning and end of ring clearly visible. The stopper construction is somewhat unique in my experience. The shank/plug is pressed before being ground, evidenced by two mold marks at the transition from the flutes on the neck of the stopper to the top of the plug. The latticino hollow " head"? of the stopper has been applied while hot. The small area above the pressed flutes and below the latticino head has been ground and polished.
I assume if Italian it would most likely have been a completely blown stopper. but not well versed in their methods.
Lean towards a possible date around 3rd quarter 19th c. Any thoughts/ ideas much appreciated.