Roberto Coin 18k Gold Ring. SEND OFFERS Roberto Coin includes the ruby on the inside of the band, and the Band has "RC" stamped too. This ring has been tested and is a tri-color ring, with white, yellow and rose gold, real natural diamonds and a real natural ruby. Size: ~10 1/2 Offers please, I am not expecting this to sell for 2,000. The ring does not come with authentication paperwork.