Mark Shand was having a very good night. The wildly charismatic 62-year-old explorer, author, conservationist, semi-retired playboy, and adored younger brother of Camilla, Duchess of Cornwall, the wife of Prince Charles, had spent six months in New York putting together the Faberge Big Egg Hunt, a huge public-art and charity event. Nearly 300 artists, architects, photographers, and designers, including Julian Schnabel, Zaha Hadid, Ralph Lauren, and Carolina Herrera, had decorated three-foot-high fiberglass eggs provided by Faberge, which were then placed throughout the five boroughs in the weeks preceding Easter. Now, on the evening of April 22, 2014, three dozen of these eggs were being auctioned at Sotheby’s to benefit Elephant Family, the nonprofit founded by Shand in 2002 to save Asian elephants and their habitats in India and 12 other…