A rare ring, set with sapphire, emerald and garnets and once owned by a medieval bishop, is coming to auction on March 26 sale of jewelry, silver, and objets d’art at Noonans Mayfair, in London.

Forbes contributors publish independent expert analyses and insights. I cover upmarket jewelry, timepieces & ethical, sustainable jewelry. London-based jeweler Dermot Fowler's "Vanity Fair' necklace ...