Gatsby Jewellery Ltd has dated this piece to the 1920s.

Accompanied by an independent jewellery report from IGR (#30310582).
Cut – Old European cut.
Colour – H.
Clarity – SI1 (clean to the naked eye).
Carat – 0.86.
Circa – 1920.
Size – M (UK) or 6 (US). Complimentary sizing is available, can be sized up or down.
Measurements – The diamond is 6.4 x 6.25mm. Sits 5.75mm from the finger.
Weight – 2.92 grams.
Metal – 18k gold. Tested.
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