Tanzanite or Sapphire and Diamond Yellow Gold Ring.

Center stone is an oval blue/purple color strong: either sapphire or tanzanite. I’m not sure. It’s a beautiful color. The diamonds are approximately 4pts each, so total carat weight of .40 carats. NATURAL DIAMONDS Finger size 6.25. The manufacturer stamp is CBI 14k. My google research says: A CBI stamp on jewelry refers to a diamond that has been cut by CBI Diamonds, a company that specializes in diamond cutting and education. CBI diamonds are cut using advanced technology to maximize their color, clarity, and visible carat. CBI diamonds are known for their precision and consistency, and the company only produces 1,000 diamonds per year.