Gatsby Jewellery Ltd has dated this piece to the 1930s.

Cut – Oval cut.
Clarity – One visible inclusion (which can be seen clearly in the pictures).
Carat – 3.32.
Circa – 1930.
Size – L (UK) or 5.5 (US). Complimentary sizing is available, can be sized up or down.
Measurements – The opal is 13.5 x 11.25mm and sits 5.25mm from the finger.
Metal – Platinum. French hallmarks.
Gatsby Jewellery Ltd has dated this piece to the 1930s.
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