18k Gold Onyx Flexible Ring

18k Tiffany & Co. onyx flexible ring.Markings: The underside of the ring is marked "TIFFANY & CO 18KRS FRANCE." The outside of the ring is marked with initials that are hard to make out (SB, or SIB, or STB) and 18k. When I asked Tiffany's about these particular markings, they told me that some older estate pieces are marked in less common ways. Size: Ring size 5-5.25. This was professionally cleaned and polished by the Tiffany store in downtown San Francisco. There is no box, but it will come with a new Tiffany's blue pouch (provided by the store at the time of polishing).