This is a beautiful Native American Navajo sterling silver ring a great green turquoise center stone. I believe this is Colorado turquoise. It is unsigned, but tested sterling silver. I do not polish my vintage/antique sterling jewelry with stones. It has light wear and tarnish but overall a lovely ring that would look exceptional after a polish. Ring is size 6. Stone measures approx 1/2" x 1/4". Weighs 3.6 grams