Zodiac Ring with all 12 birthstones and large center stone

I have been collecting vintage and antique jewelry for years. My father bought a house about 15 years ago and there were several boxes filled with old jewelry just collecting dust. Luckily my grandmother saved these items and gave them to me before she passed away. The man who had previously lived in that house was nearly 90 years when he passed away. This ring was in the house and I can't seem to identify it. It has been in my possession for about 8 years now. Someone once told me that the center stone represents the sun with all 12 birthstones surrounding it. I have also researched items with all 12 birthstones and the main thing I can find is a story about Aaron's breastplate. If anyone has any information about this item, I would greatly appreciate it.