Hi ,
I think you need to look elsewhere for the origin of this 1 , i would think its Saxon or Bohemian , the facet cut bowl and knop and the type of decoration suggest this to me , la Granja decoration is usually engraved before gilding and usually a stylized type of rose or other flowers.
As to date i would think mid 18th c ,what was it used for ?? getting drunk !!! , large goblets are thought to have been used in civil and public ceremonies and gatherings , weddings etc for communal drinking,those who are members of the Glass association can view the selection of 50 goblets which I displayed at the Cambridge glass fair a few years ago , some with a capacity of 2 litres and more.
The gilding should be left alone , apart from being a very expensive(more than its final value) job to have it properly done ,it's just not the done thing for reasons already mentioned .
Below is a 14 ins goblet from the exhibition which I catalogued as Bohemian. (stem with repair)
cheers ,
Peter.