Gatsby Jewellery Ltd has dated this piece to the 1920s.
The stone is secured in a platinum collet with four split claw, with geometric detailing in the gallery, leading to a slender 18k yellow gold shank set with ten (five each side) eight-cut diamonds in the milgrained shoulders.

Accompanied by a Natural Diamond Grading Report from HRD Antwerp (#210000182417).
Cut – Old mine cut in the centre. The diamonds in the shoulders are eight-cuts.
Colour – G in the centre. The diamonds in the shoulders are F to G.

Clarity – VVS1 in the centre. The diamonds in the shoulders are VS1 to VS2.
Carat –0.86 in the centre, with approximately 0.07 carat in the shoulders.
Circa – 1920.
Size – M 1/2 (UK) or 6.25 (US). Complimentary sizing is available, can be sized up or down.
Measurements – The diamond is 5.44 x 5.33mm. Sits 6.2mm from the finger.
Metal – 18k yellow gold and platinum. 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