Hi ,
I think it has all been said really,yes probably Silesian and 18th c ,as to special I would say not , the glass form is fairly standard and its the decoration that can make some of this form "special" though from what I can see the decoration on yours is fairly basic with no great quality or significance,having said that though "special"is not always required as long as the glass appeals and the price is right with thoughts of investment not in mind .
cheers ,
Peter.