Elegant Goldtone and Large CZ Ladies Ring

This ring came from an auction, so I know very little about it. I assume it is costume jewelry, but it is very ritzy looking and is goldtone metal with a large CZ in the center. It looks to be about a size 6 or 7, but measures approx. 3/4 inches across the opening. It is unmarked. It is in very good condition, no noticeable wear.