Rare Aqua Glass Two Handled Loving Cup Tyg

A very unusual piece of glass in the form of a hollow two handled loving cup or tyg. The piece is free blown with pontil mark to base and nice folded foot. Even more unusual is a small glass seal stamped on the side with emblem of a castle surrounded by water. The closest I can get to attributing this piece is a flag associated with the town of Trogir in Croatia which had a glass blowing history within the area, image attached. Small chip to rim otherwise in good condition. A great piece of glass and the first of its type I have seen. Early to mid 19th century.