Thank you for contacting Mearto with your appraisal inquiry.

It is a beautiful vintage/antique ring. Such antique jewellery are being offered at auction on a regular basis.
It is set in what looks like 14kt yellow gold, the stone is cut in an oblong shape, and based on the photos I would say that it is malachite. It is a beautiful green stone with a deep interchanging colour and a lovely unique look. The design of the ring is very becoming and elegant. It was probably made in the 1940s-1950s when this particular shape of stones was very popular combined with the very simple style of the ring. Two good materials combined.

I believe that tis beautiful ring would attract the attention of both collectors and dealers if it came up for auction.
The estimate provided is for a well-advertised specialised online jewellery auction, where I believe the ring has the best chance of realising its fullest potential. However, there is no measurement for the sentimental value you might attach to your grandmothers ring. Retail "asking prices" can be higher and vary.

Please let me know if you have any additional questions. I’m happy to help.
Thank you