AMNH's Halls Of Gems & Minerals To Reopen With New Look This June arrow The new Allison and Roberto Mignone Halls of Gems and Minerals, which are scheduled to open to the public on June 12, 2021, at the American Museum of Natural History. The 11,000-square-foot halls will display one of the greatest collections of its kind and engage visitors in the recent science about our dynamic planet. View all 9 Ever since I was taken on a journey through the inner bowels of an opal during the opening credits of the Safdie Brothers classic Uncut Gems, I have had a hankering to stare at precious stones in real life, and yet have been presented with few options for actually doing so. After a four-year closure, however, one of the premier locations for gem-gazing in NYC, the Mignone Halls of Gems and Minerals in the American Museum Of Natural History, will reopen on June 12th.