UV Rays Shed New Light on the Hope Diamond’s Mysterious Red Glow
Hundreds of rare precious gemstones are on display in the Gems and Minerals Galleries at the Smithsonian’s National Museum of Natural History. According to Dr. Jeff Post, curator of the United States National Gem and Mineral Collection and avid mineralogist, few of those gems garner more attention than the world famous and Smithsonian’s own, Hope Diamond. With its breathtaking beauty and mysterious past, the Hope Diamond intrigues millions of museum visitors each year; but beyond its rumored curse, the world’s largest blue diamond is proving to be a unique scientific specimen.
The 45.52-carat blue diamond puzzles scientists because of the fiery red glow it gives off for several minutes after being exposed to ultra-violet light. Scientists refer to this phenomenon as phosphorescence. “It looks like a glowing orange coal in your barbeque grill,” explains Post. “It has been described as one of the unique properties of this unique diamond, something special to the Hope Diamond.” No comprehensive studies on the nature of the phosphorescence exist, which has made Dr. Jeff Post question the impressive glow for years. “There didn’t seem to be a lot of consistency, or certainly no quantification of the nature of the phosphorescence,” Post says. Thus, he and a team of researchers took on the challenge to dispel the deep dark secrets of the Hope Diamond.
The 45.52 carat Hope Diamond is in a platinum setting surrounded by sixteen white pear-shaped and cushion-cut diamonds designed by Pierre Cartier in about 1910. Photograph by Chip Clark.
In a curious effort, Post and colleagues from the U.S. Naval Research Laboratory, Ocean Optics Instrument Company, and Penn State University eagerly snagged the Hope Diamond from its glass enclosure, along with the world’s second largest deep-blue diamond, the Blue Heart Diamond, and blue diamonds from the Aurora Butterfly of Peace, a temporary collection of 240 colored gemstones. They hand carried the gems to the Smithsonian’s highly secure blue room vault, where hundreds of the museum’s most expensive and rare gems are located. Using a portable instrument that measures wavelengths of light, known as a spectrometer, the researchers exposed each diamond to ultra-violet light in order to measure the intensity of light given off, and the rate at which it faded. As reported in the January 2008 issue of the journal Geology, the researchers developed a better understanding of phosphorescence behavior, and to their pleasant surprise, discovered a way to essentially “fingerprint” blue diamonds.
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