| The Hope Diamond is a 45.52-carat, deep-blue diamond that sits center stage in the Smithsonian Institution's United States Gem Collection. The object of intrigue for almost four centuries, the diamond has more recently been puzzling scientists because of the deep red glow it gives off for several seconds after being bathed in ultraviolet light.
"It was thought to be quite rare," said Naval Research Laboratory gem researcher Sally Magaņa. "It added to its intrigue and mystery."
Magaņa led a team of researchers studying the phosphorescence of the Hope Diamond and 66 other rare natural blue diamonds -- including the world's second-largest Blue Heart blue diamond. The diamonds were available briefly at the same location from the Aurora Heart and Aurora Butterfly diamond collections.
They used the latest digital spectral measurement devices to measure the wavelengths of light emitted by the diamonds, along with the rate the glowing faded. Their results appear in the January issue of the journal Geology.
The researchers discovered that, in fact, all natural blue diamonds phosphoresce with red or blue-green light in various individual, quirky ways. Some, like the Hope Diamond, give off far less green-blue light, which allows their red glow to dominate. The cause of the phosphorescence is primarily the element boron, although the finer details of the visual effect are still not worked out, she said.
"It's really not that rare," Magaņa told Discovery News, of the Hope Diamond's glow.
Nor is the Hope Diamond the best at the glow-in-the-dark trick, she said, "It's not the longest lasting or the most intense."
Other blue diamonds glow red, she said, and some glow much longer -- up to 28 seconds in one case, compared to the Hope Diamond's 8.2-second glow.
That said, there's no denying that the size of the Hope Diamond makes the natural special effect more impressive.
"Because it's so large it looks like a fiery coal in your hand," said Magaņa.
What may be more important, however, is that the unique mix of colors given off by different individual diamonds, combined with each diamond's individual rate of fading, provide a new way to fingerprint any natural blue diamond, explained Magaņa, who recently moved to the Gemological Institute of America.
That means some long-standing questions about whether certain smaller stones were really cut from larger stones can be sorted out once and for all. They all should share the same phosphorescent signature.
Discovery News
The Hope Diamond's history can be easily traced to a blue diamond named the Tavernier Blue, which was originally mined from the Kollur mine in Golconda, India, and was a crudely cut triangle shape of 115 carats (22.44 g). French merchant-traveler Jean-Baptiste Tavernier purchased it sometime in 1660 or 1661. According to legend, the Tavernier Blue had been stolen from an eye of a sculpted idol of the Hindu goddess Sita, the wife of Rama, the Seventh Avatara of Vishnu.
In 1668, Tavernier sold the diamond to King Louis XIV of France. Sieur Pitau, the court jeweller, cut it and produced a 67 1/8 carat (13.4 g) stone. The stone became known as the Blue Diamond of the Crown or the French Blue.
When Louis XVI of France became king, he gave the diamond to Marie Antoinette to add to her collection of jewelry. During the French Revolution, while Louis XVI and Marie Antoinette were held in prison, the pendant with the diamond was stolen.
The Hope diamond was recorded in the possession of a London diamond merchant Daniel Eliason in September 1812, which marks the earliest point that the exact history of the Hope Diamond can be definitively fixed. This diamond was generally believed to have been cut from the French Blue, a fact which was finally verified in 2005. It is often pointed out that the Hope Diamond came into recorded history almost exactly 20 years after the theft of the French Blue, just as the statute of limitations for the crime had expired.
The diamond next resurfaced in the gem collection of Henry Philip Hope in 1824. in 1910, Pierre Cartier bought it for 550,000 francs.
Cartier re-set the stone and in 1911 sold it to U.S. socialite Evalyn Walsh McLean, who in 1949 sold it to New York diamond merchant Harry Winston, who donated it to the Smithsonian Institution on November 10, 1958, sending it through U.S. Mail in a plain brown paper bag.
The Hope Diamond is now part of the National Gem Collection in the Smithsonian Institution, in the National Museum of Natural History. At first, it was placed inside a glass-fronted safe in a gem hall. In 1962, it was lent to an exhibition of French jewellery in Paris and in 1965 to South Africa to the Rand Easter Show.
On February 9, 2005, the Smithsonian Institution published the findings of its year-long computer-aided geometry research on the gem and officially acknowledged the Hope Diamond is part of the stolen French Blue crown jewel. | |
