It was listed by Exhibit Antiques. Sold pieces stay on Sellingantiques as a record of what has passed through, and the next one is rarely far away.
Exhibit Antiques has dated this piece to the Georgian era.
England, c1750. Period of George II.
Condition
Excellent, age-related wear as shown, no chips cracks or restoration
Dimensions
Height: 15.9cm Rim diameter: 5.3cm Foot diameter: 7.1cm.
Technical Description
Conical foot with a snapped pontil.

Comments
This is a 'true' mercury twist and quite rare..even more so to find an engraved example.
You often see double series air twist stems being described as double series mercury twists...but I'm afraid the definition shows a lack of knowledge and is incorrect. A mercury twist is always a single series.
Exhibit Antiques has dated this piece to the Georgian era.
Specialists in 18th & 19th century antique glass
You can view the stock and full dealer information on the Exhibit Antiques Profile Page