The ring size, as indicated by the photograph, appears to be about 5.75.
In that I have a no return policy. I would welcome any questions that you might have prior to purchase. Please examine the photos carefully as I have tried to show any defects that I may have seen. Feel free to contact me, and I will help you to the best of my ability.
I have tried to size it with a ring sizer, and the photograph may be more accurate than my own estimation.
This piece of jewelry comes from my mom's estate. Where I think a ring is to be valued under $500, it is pointless to pay for an expensive appraisal, when the appraisal might cost more than the piece of jewelry. So, I have done my best to approximately measure it in inches, since most of the people who are purchasing on eBay are in the United States. Many of these had been in my mom's possession for 30-50 years. Furthermore, pictures have been taken showing the approximate ring size to make it easier for you to determine whether it might be a fit or you may have to have it sized.