It's possible that this is something from Erickson (Erickson Freehand Glass), Ohio, States. In the 1940's and '50's they knocked out a lot of designs some of which had this two tone (often green and white) colourway - many of which had this heavy 'paperweight' sort of bulbous base. They were also known for producing 'bullicante' (bubbled) pieces, and much of their design incluence was taken from Scandinavia - believe the owner was Carl Erickson and obviously he introduced a Swedish flavour to the factory's designs, which is apparent in much of their work.
Could be wrong but had a feeling that Anita might have some knowledge of this production - or maybe Ken. Don't know if the factory folded or is still going.
W/F's put bubbles in via a mould in some of their earlier glass, but not sure about later designs - the guys who did air twists used a small wooden holder with metal pins in some kind of circular pattern before stretching the stems etc.
Would imagine jp might have a better explanation of this process.
Welcome to Christmas Day 2013.