FLORENCE, Italy — It was the last piece to go on the auction block: a life-size sculpture in creamy Carrara marble of the Italian opera singer Andrea Bocelli reclining in a ornate, oversized chair.

“Exquisite,” said the actress Sharon Stone, serving as the celebrity auctioneer for a charity event in September at Florence’s Palazzo Vecchio. She then asked the piece’s creator, Gualtiero Vanelli, to come on stage with her. Read more