Gatsby Jewellery Ltd has dated this piece to the 1950s.
Extraordinarily, the diamond is fully embedded within a round, deep blue sapphire which is itself rubover set in yellow gold. The diamond set, platinum shoulders conform to a slim, D-shaped yellow gold shank. Utterly masterful.

Accompanied by an independent jewellery report from IGR (#30308690).
Cut – Old European cut in the centre with eight-cut diamonds in the shoulders. The sapphire is a round mixed cut.
Colour – The centre diamond is light yellow, with G to H diamonds in the shoulders.

Clarity – The centre diamond is VS2. The diamonds in the shoulders are SI1 to I1 (all are clean to the naked eye.
Carat – The centre stone is approximately 0.84 carat, with a further approximate 0.06 carat in the shoulders. The sapphire is approximately 2.25 carat

Circa – 1950.
Size – J (UK) or 4 5/8 (US). Complimentary sizing is available, can be sized up or down.
Measurements – The head of the ring is 9.8 x 9.6mm. Sits 6.5mm from the finger.
Metal – 18k yellow gold and platinum. Tested.
Gatsby Jewellery Ltd has dated this piece to the 1950s.
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