AgAu Jewellery has dated this piece to the 1920s.
Each shoulder has three single-cut diamonds mounted in Platinum. Total diamond content approx. 0.6ct.

Hallmarked 18ct & Plat
UK size M1/2
A Beautiful Art Deco Diamond solitaire ring featuring a 5mm European-cut Diamond, mounted in a claw setting with diamond mounted shoulders. Each shoulder has three single-cut diamonds mounted in Platinum.
AgAu Jewellery has dated this piece to the 1920s.
Agau jewellery offer an extensive range of 9ct and 18ct gold jewellery.
You can view the stock and full dealer information on the AgAu Jewellery Profile Page