COMINGS AND GOINGS Bryan Morgan (pictured), former chief operating officer of Signet, has joined Stuller as chief systems and technology officer. GIA has welcomed three new governors to its board: Andy Johnson, CEO of Diamond Cellar Holdings; Lawrence Ma, chief executive of Lee Heng Diamond Group; and Karen Evans, national director of the U.S. Cyber Challenge. The Israel Diamond Exchange has reelected Yoram Dvash for a second three-year term as bourse president. Blue Nile has appointed David Yurman veteran Ruth Sommers (pictured) chief operating officer. She most recently served as Yurman’s COO. In addition, former Tiffany & Co. CEO Frédéric Cumenal has joined Blue Nile’s board. De Beers executive head of strategy and corporate affairs Gareth Mostyn is leaving the company after six years. He will join the Church of England as chief finance and operations officer. Austr