The Hope Diamond is a 45.52-carat (9.104 g) diamond originally extracted in the 17th century from the Kollur Mine in Guntur, India. It is blue in color due to trace amounts of boron. Its exceptional size has revealed new information about the formation of diamonds.The stone is known as one of the Golconda diamonds. The earliest records of the diamond show that French gem merchant Jean-Baptiste Tavernier purchased it in 1666 as the Tavernier Blue. The stone was cut and renamed the French Blue (Le bleu de France); Tavernier sold the stone to King Louis XIV of France in 1668. It was stolen in 1791 and re-cut, with the largest section of the diamond appearing under the Hope name in an 1839 gem catalogue from the Hope banking family.

The diamond has had several owners, including Washington socialite Evalyn Walsh McLean, who was often seen wearing it. New York gem merchant Harry Winston purchased the diamond in 1949, touring it for several years before donating it in 1958 to the National Museum of Natural History in the United States, where it is on permanent exhibition.

People typically think of the Hope Diamond as a historic gem, but... it's [important] as a rare scientific specimen that can provide vital insights into our knowledge of diamonds and how they are formed in the earth.