Cushion cut citrine gemstone cocktail ring.

This is known to be a real cushion-cut citrine gemstone cocktail ring. Won it 10 years ago at a silent auction but since it doesn’t fit me as I am a size 6 it is considered to be too small. Unfortunately I do not know the size and because it is too small I never got to wear it. All I know is that it had to be smaller than a size 6 as again that is my size. If I had to guess I would say size 5-5 1/2.