Double Series Air Twist Composite Stem Georgian Wine Glass c1750

Heading : Double series air twist composite stem wine glass
Period : George II - c1750
Origin : England 
Colour : Clear
Bowl : Trumpet 
Stem : Composite 
Stem Features : Plain stem section above multi spiral air twist outwith vertical air column. Air twist section has one ball knop and one swelling knop
Foot : Conical 
Pontil : Snapped 
Glass Type : Lead 
Size :  16.3cm height, 6.8cm diameter bowl, 7.5cm diameter foot
Condition : Excellent, no chips or cracks 
Restoration : None 
Weight: 170 grams

References: 

Glass Through the Ages by E. Barrington-Haynes Pl. 72