Hope Diamond

The Hope Diamond is a 45.52-carat (9.104 g; 0.3211 oz) blue diamond that has been famed for its great size and blue-violet color since the 17th century. It was extracted in the 17th century from the Kollur Mine in Andhra Pradesh, India. The gemstone's exceptional size has revealed new information about the formation of diamonds.

The Hope Diamond's recorded history begins in 1666, when the French gem merchant Jean-Baptiste Tavernier purchased the raw Golconda stone in India. After cutting the gem and renaming it "the French Blue" (Le bleu de France), Tavernier sold it to King Louis XIV of France in 1668. It was stolen in 1792, re-cut by persons unknown, and recovered after a lapse of years, appearing under the Hope name in an 1839 gem catalogue from the Hope banking family, from whom the diamond's name derives.

The Hope Diamond's last private owner was the American jeweler Harry Winston, who bought it in 1949 from the estate of the mining heiress and socialite Evalyn Walsh McLean. After exhibiting the diamond on tour for several years, Winston set it in a necklace and donated it in 1958 to the Smithsonian Institution's National Museum of Natural History in Washington, D.C., where it remains on permanent exhibition.

Classification

The Hope Diamond is a large, 45.52-carat (9.104 g; 0.3211 oz), deep-blue diamond, studded in a pendant Toison d ’or. It is a dark greyish-blue color under ordinary light due to trace amounts of boron within its crystal structure, and it exhibits a red phosphorescence under exposure to ultraviolet light. It is classified as a type IIb diamond.

The Hope Diamond is currently housed in the National Gem and Mineral collection at the National Museum of Natural History in Washington, D.C. It has changed hands numerous times on its way from Hyderabad, India, to France, Great Britain, and the United States, where it is on public display. It has been described as the "most famous diamond in the world".

Physical properties

• Weight: In December 1988, the Gemological Institute of America's laboratory determined the diamond to weigh 45.52 carats (9.104 g; 0.3211 oz).
• Size and shape: The diamond has been compared in size and shape to a pigeon egg or a walnut that is pear-shaped. The length, width, and depth are 25.60 mm × 21.78 mm × 12.00 mm (1 in × 7/8 in × 15/32 in).
• Color: It has been described as being a "fancy dark greyish-blue" as well as "dark blue in color," or having a "steely-blue" color. Blue diamonds similar to the Hope can be shown by colorimetric measurements to be grayer (lower in saturation) than blue sapphires. In 1996, the Gemological Institute of America examined the diamond and, using their proprietary scale, graded it fancy deep grayish blue.

Visually, the gray modifier (mask) is so dark (indigo) that it produces an "inky" effect, appearing almost blackish-blue in incandescent light. Current photographs of the Hope Diamond use high-intensity light sources that tend to maximize the brilliance of gemstones. In popular literature, many superlatives have been used to describe the Hope Diamond as a "superfine deep blue," often comparing it to the color of a fine sapphire—for example, "blue of the most beautiful blue sapphire" (Deulafait)—and describing its color as "a sapphire blue." Tavernier described it as a "beautiful violet".

• Phosphorescence: The stone exhibits an unusually intense, brilliant red phosphorescence after exposure to short-wave ultraviolet light. This 'glow-in-the-dark' effect persists for some time after the light source has been switched off, and this strange quality may have helped fuel its reputation of being "cursed." The red glow is a phenomenon of blue diamonds that helps scientists "fingerprint" them, allowing them to distinguish real ones from artificial ones. The red glow occurs because of a mixture of boron and nitrogen in the stone.
• Clarity: The clarity was determined to be VS1, with whitish graining present.
• Cut: The cut was described as being "cushion antique brilliant with a faceted girdle and extra facets on the pavilion."
• Chemical composition: In 2010, the diamond was removed from its setting to measure its chemical composition. After boring a hole one nanometer deep, preliminary experiments detected the presence of boron, hydrogen, and possibly nitrogen; the boron concentration varies from zero to eight parts per million. The boron is the cause of the stone's blue color.
• Touch and feel: When the Associated Press reporter Ron Edmonds was allowed by Smithsonian officials to hold the gem in his hands in 2003, he wrote that the first thought that had come into his mind was, "Wow!" It was described as "cool to the touch." He wrote:

You cradle the 45.5-carat stone—about the size of a walnut and heavier than its translucence makes it appear—turning it from side to side as the light flashes from its facets, knowing it's the hardest natural material yet fearful of dropping it.

• Hardness: Diamonds in general, including the Hope Diamond, are the hardest natural minerals known on Earth, but, because of weak planes in the bonds of a diamond's crystalline structure, the crystal can fracture along these planes if not handled correctly. These weak planes allow diamond cutters to split a rough uncut stone into smaller flawless parts before the process of faceting the stone takes place. Only a diamond can scratch another diamond, so, to be faceted, the uncut rough diamond is mounted in a holder, and then the flat surfaces or facets are ground into the surface of the stone using specially made metal wheels impregnated with diamond particles. These facets are ground and polished with ever finer grades/grits of diamond powder until they have a clear mirror surface, ultimately producing a gem that sparkles by refracting and reflecting light in different ways.

History

Geological beginnings

The Hope Diamond was formed deep within the Earth approximately 1.1 billion years ago. Like all diamonds, it was formed by carbon atoms strongly bonding together. The Hope Diamond was originally embedded in kimberlite and was later extracted and refined to form the current gem. The Hope Diamond contains trace amounts of boron atoms intermixed with the carbon structure, which results in the rare blue color of the diamond.

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.

India

Several accounts, based on remarks written by French gem merchant Jean-Baptiste Tavernier, who obtained the gem in India in 1666, suggest that the gemstone originated in India, in the Kollur mine in the Guntur district of Andhra Pradesh (which, at the time, was part of the Golconda kingdom of the Qutb Shahi dynasty).

Tavernier's book, the Six Voyages (French: Les Six Voyages de J. B. Tavernier), contains sketches of several large diamonds that he sold to King Louis XIV, possibly in 1668 or 1669; a blue diamond is shown among these, and Tavernier mentions the mines at "Gani Coulour" (Kollur Mine) as a source of colored diamonds, but no direct mention of the stone is made. Historian Richard Kurin has built a highly speculative case for 1653 as the year of acquisition, but the most that can be said with certainty is that Tavernier obtained the blue diamond during one of his five voyages to India between the years 1640 and 1667. One report suggests he took 25 diamonds to Paris, including the large rock which became the Hope, and sold all of them to King Louis XIV. Another report suggested that in 1669, Tavernier sold this large blue diamond along with approximately one thousand other diamonds to King Louis XIV for 220,000 livres—the equivalent of 147 kilograms of pure gold.

In the historical novel, The French Blue, gemologist and historian Richard W. Wise proposes that the patent of nobility granted to Tavernier by Louis XIV was part of the payment for the Tavernier Blue. According to the theory, Jean-Baptiste Colbert (the King's Finance Minister at the time) regularly sold noble offices and titles for cash; an outright patent of nobility, according to Wise, was worth approximately 500,000 livres. That amount, plus the reported sale to the King, would have totaled about 720,000 livres, half the price of Tavernier's initial estimate for the gem. There has been controversy regarding the actual weight of the stone: Morel believed that the 112.1875-carat (22.43750 g; 0.791460 oz) stated in Tavernier's invoice would be in old French carats, thus 115.28 metric carats.

France

In 1678, Louis XIV commissioned the court jeweler Jean Pitau to recut the Tavernier Blue, resulting in a 67.125-carat (13.4250 g; 0.47355 oz) stone which royal inventories thereafter listed as the Blue Diamond of the Crown of France (French: diamant bleu de la Couronne de France). Later English-speaking historians have simply called it the French Blue. The king had the stone set on a cravat-pin.