Thank you for contacting Mearto with your appraisal inquiry.

It is a beautiful ring set with a red stone and two diamonds. Such vintage rings and jewellery are being offered at auction on a regular basis. This design has been made for many years and is still very popular due to its elegance and simple design.
I am afraid I cannot determine what type of stone the red stone is just from the photos, that would need thorough examination in real life by a gemmologist. However if I presume that it is a ruby with two diamonds in a gold ring made in the second half of the 20th century.

The estimate provided is for a well-advertised specialised online jewellery auction, where I believe the gold ring has the best chance of realising its fullest potential. However, there is no measurement for the sentimental value you might attach to the lovely 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