People with plenty of loot of their own got the chance to bid for gold, silver and gems found by treasure hunter Mel Fisher on the shipwrecked Spanish galleon Nuestra Senora de Atocha – one of the greatest hauls of treasure ever recovered from the sea.

After a 16-year search, in September 1985, the aptly named Fisher and his crew found the wreck and hauled up 40 tonnes of gold and silver, including more than 100,000 Spanish silver coins known as Pieces of Eight, along with Colombian emeralds and other artefacts – together worth an estimated $500m (£320m).

The Atocha was heading back to Spain with a load of gold and silver from the New World when it sank and broke up in a hurricane not far from Key West in September 1622. Part of the haul went under the hammer at Guernsey's auction house in New York on Wednesday 5 August.

The auction house's president Arlan Ettinger was contacted several months ago by Fisher's children who wanted to honour the will of his widow and business partner, Dolores, who died six years ago. She wanted the the items sold with a portion of the money going to the Have a Heart Foundation, which places defibrillators in US public schools. The family had retained some of the items from the wreck that were never before seen.

"The gold chalice is breathtaking," Ettinger said. "There is a little gold frame with extraordinary filigree work that you marvel how people could have done that and then marvel even more to think that this was under water for almost four centuries and how it looks like it was made yesterday, so those certainly stand out.

"The gold and emerald cross is magnificent. And then there were, I believe about 12,000 pearls, natural pearls that were discovered in the wreckage and the two largest and presumably most valuable of those are here too and those are quite breathtaking. So those are just a few of the items that strike my fancy."