One of the most visited wonders of the Smithsonian's National Museum of Natural History, the gem was out of its security case for scientific study Thursday when curators — tense security guards hovering nearby — allowed a reporter and photographer to briefly hold the famed stone.
What does it feel like to hold one of the world's most priceless gems?
"The first thought that comes to mind is 'Wow!'" wrote the Associated Press' Randolph E. Schmid.
"It's like holding a bit of ancient India, the French Revolution, Georgian England and Gilded Age America in one magnificent moment," Schmid said.
"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," he added.
Once part of the French crown jewels, the fabled gem is now the star of the Smithsonian's National Museum of Natural History. It normally resides in a special protective display case in a secure room.
For the testing it was taken to a museum laboratory, reachable down winding corridors and through three locked doors. It was only the second time in 20 years the Hope has been removed from its necklace setting, where it is surrounded by bright, clear diamonds that intensify its blue color.
National Gem Collection Curator Jeffrey Post ordered the lights turned off and focused an ultraviolet beam on the Hope Diamond. Then he switched off the beam and, in pitch dark, the diamond glowed bright orange-amber.
It's that strong color, which lasts for several seconds after the diamond is exposed to ultraviolet light, that intrigues scientists. What causes the gem to fluoresce remains a mystery — Post speculates it's related to chemical impurities that give it that blue color.
But the Hope Diamond has inspired legends over the years, and some may prefer those to sheer science.
Some say, for instance, that the glowing color reflects the blood of royalty spilled in the French Revolution and the trail of bad luck said to have followed the stone over many years — including the bankruptcy of the Hope family for whom it is named and the death of the young son of later owner Evalyn McLean.
The claimed curse notwithstanding, this diamond has been nothing but good luck for the Smithsonian, Post said. Attendance jumped after jeweler Harry Winston donated it to the museum in 1958, he said, and that gift spurred others, helping the museum to build its world-class gem collection.
Winston, by the way, mailed the gem to the Smithsonian, insuring it for $1 million for a fee of $142.85, plus $2.44 postage. The package itself is on display at the Smithsonian's National Postal Museum.
Two more of the world's best blue diamonds were also on hand for the research: the Smithsonian's Blue Heart, 30.8 carats, and the Steinmetz Heart of Eternity, 27.6 carats.
The Hope is slightly blue-gray compared with the other two. The Hope was mined in India and the others in South Africa, so they shouldn't be expected to be exactly the same, Post explained.
Both of the other stones also glowed following exposure to ultraviolet light, but only briefly compared with the Hope. The Steinmetz also glowed amber while the Blue Heart had a brief white glow.
The blue color of the stones is caused by the element boron mixed into the carbon of the diamonds, Post said, and part of the testing was to use infrared light to get a chemical spectrum from the gems. The results are still being studied, but Post said tests did confirm that boron was present.
Scientific analysis of the diamonds had to wait until the Smithsonian had the instruments to conduct the work, since taking the diamond somewhere else would be a security problem, Post said.
The Hope Diamond was returned to its necklace setting and display case Thursday morning in time for visitors to begin walking past, unaware the stone had been away from its normal resting place. The Blue Heart was also back in its case at the museum, while the Steinmetz is being returned to its owner after being on loan to the museum for several months.