The Hope Diamond is one of the legendary jewels of history, with ownership records dating back almost four centuries. Its much-admired rare blue colour is due to trace amounts of boron atoms. Weighing 45.52 carats, its exceptional size has revealed new findings about the formation of gemstones. The jewel is believed to have originated in India, and is known to have been cut from the French Blue (Le bleu de France), presented to King Louis XIV. It acquired its name when it appeared in the catalogue of a gem collection owned by a London banking family called Hope in 1839. Later it was sold to Washington socialite Evalyn Walsh McLean who was often seen wearing it. Since 1958, it has been on exhibition at Washington’s National Museum of Natural History.