(IDEX Online) - A long-lost emerald, salvaged from a 400-year-old shipwreck is to be auctioned by Sotheby's New York.The octagonal step-cut 6.25 carat emerald ring will be sold with a $50,000 to $70,000 estimate and all proceeds will go to humanitarian efforts in Ukraine.The gemstone was lost for 363 years after the galleon Nuestra Senora de Atocha sank during the hurricane season in the Florida Keys.Divers had long dreamed of locating the elusive wreck. In 1985 a team led Mel Fisher was successful.In addition to the emerald, they found an incredible treasure trove of 180,000, 24 tons of ingots struck from Bolivian silver and 125 bars of gold bullion extracted from the Caribbean, Mexico and the Andes.The emerald is being sold by the author and philanthropist Mitzi Perdue. It was an engagement gift from her late husband Frank Perdue in 1998.It will be sold at Sotheby's Magnificent Jewels auction on 7 December.Pic shows the ring and Mitzi Perdue (wearing the ring) with late husband Frank Perdue.