This is a very good English, hand-blown, Heavy Baluster wine drinking glass, dating to the early 18th century, circa 1710, English queen Anne period.
Heavy baluster glasses are rare and very collectable, representing the finest of English drinking glasses. This is a tall, very heavy grey coloured example.
It is handblown from English lead glass. These very early glasses had a larger lead content, making them heavier and giving them a darker grey color compared with glasses later in the 18th century. 
The glass has the usual striations, inclusions and tiny bubbles you would expect to see in 18th century glass, which gives these glasses their unique charm, with no two glasses being the same.
This glass has a small drawn trumpet bowl with a solid glass base and sits on a heavy inverted baluster knop stem enclosing a long heart shaped air tear with a very thick shaped stem. The stem leads to a good wide conical folded foot having a rough snapped-off pontil mark to the underside.
Similar glasses are illustrated in L.M. Bickerton's excellent book called Eighteenth Century English Drinking Glasses, published by The Antique Collectors' Club. See pages 64 to 82. 
Dimensions:
Rim diameter: 2.57 inches.
Foot diameter: 3.23 inches.
Height: 6.64 inches.
Weight: 283 gram.
This represents a very heavy glass, relative to a later 18th century glass of the same height, which would weigh about 150 gram. 
Overall, a very beautiful early English drinking glass.