Andrew Cox Antiques has dated this piece to the 1940s.
Dimensions below.

Postage and packing :- UK £8.00.
Europe £16.00.
Outside Europe £18.00.
Condition :- Excellent, with no damage.
Hallmarks :- Tests as silver, makers mark of JD.
Date :- Circa 1940.
Height of stone :- 1.5 cms.
Height of mount :- 2.1 cms.
Width of mount :- 2.1 cms.
Ring size :- N 1/2.
Andrew Cox Antiques has dated this piece to the 1940s.
Specialists in quality antique silver, glassware, jewellery and object de vertu
You can view the stock and full dealer information on the Andrew Cox Antiques Profile Page