(IDEX Online) - French police foiled an audacious bid by thieves to blow up glass cases at the city's Museum of Natural History (pictured) and steal a 217-ct necklace made for the Queen of Egypt.The $5.8m piece is among than 500 items in the Gems exhibition, which includes minerals, gemstones and objets d'art from the museum's collection, together with over 200 jewels by Van Cleef & Arpels. Police acting on a tip-off arrested three men detonating explosives in a forest outside the capital to prepare for the heist, according to a report in Le Parisien newspaper.The necklace, which contains 673 diamonds, was made by the French jeweler Van Cleef & Arpels for Queen Nazli in 1939, was sold at auction by Sotheby's in 2015 for $5.8m.She divorced and later fled to the USA after Egypt's monarchy was overthrown in 1952 and sold her jewelry collections when she fell on hard times.