Scott Kay, one of the most prominent and celebrated designers in the ­jewelry business, died of a heart attack on Dec. 4. He was 57.He is survived by his three children and his wife of nearly 30 years, Regina.His unexpected death comes at a time when his three-decade-old company was reinvigorating itself. It had hired a CEO and was beefing up its C-suite with an impressive roster of industry talent. Kay had moved up to chairman, hoping to concentrate on designing, and had hinted at other major announcements.“I have big things cooking,” he told JCK this summer.A nationally renowned jeweler often credited with resurrecting platinum, Kay grew up in Brooklyn, N.Y., the son of an alcoholic mother and absent father.“I come from a broken home, and within that broken home there were tremendous difficulties,” he said in a biographical video. “You have a choice in life: You can either h