Gatsby Jewellery Ltd has dated this piece to the 1920s.
The diamond is mounted in a classic six claw platinum collet with an open gallery, leading to 18k yellow gold shank.

Contemporary hallmarks, London.
Cut – Old European cut.
Colour – G.
Clarity – I1.
Carat – 1.07.
Size – M (UK) or 6 (US). Complimentary sizing is available, can be sized up or down.
Measurements – The diamond is 6.75 x 6.6mm and sits 6mm from the finger.
Weight – 3.1 grams
Provenance – English
Metal – 18k yellow gold and platinum. Hallmarked.
Gatsby Jewellery Ltd has dated this piece to the 1920s.
Gatsby jewellery are a husband and wife team who have years of knowledge and experience in dealing in fine antique jewellery.
You can view the stock and full dealer information on the Gatsby Jewellery Ltd Profile Page