4. American Museum of Natural History
On October 29, 1964, two young thieves managed to break into the Hall of Gems and Minerals (now named after Harry Frank Guggenheim) at the American Museum of Natural History after hours to grab 24 priceless (and somehow uninsured) gems, including the Star of India (the world’s largest sapphire), the Midnight Star (the world’s largest black sapphire), and the De Long Star Ruby, considered the world’s most perfect ruby. The stones, in total, were worth the equivalent of approximately $3 million dollars today.
The thieves, along with another accomplice, were arrested quickly because of their own indiscretions following the heist. Tracking down the jewels, however, was a much more laborious task. To this day, only 10 of them have been recovered. The Star of India, the Midnight Star, and the De Long Star Ruby, luckily, did make their way back to the museum and continue to be prominently displayed, albeit with much more protection.