The buckle was a common feature in fashion design between World War I & World War II. It could indicate military solidarity or one’s significance to another person. Of course, since this was the era of the horse, leather & buckles were much more a part of everyday life than they are today. Even so, top classical designers like Hermes, Gucci & Ralph Lauren continue with this motif.
This particular ring is antique style, but we cannot date it with accuracy. It is size is 7.5-8, and would be perfect for either a man or a woman.