The Hope Diamond is almost undoubtedly the most famous fancy colored diamond known to man, says www.gemewizard.com. Discovered in India during the 17th Century, the 45.52-carat cut stone is housed in the Smithsonian Natural History Museum in Washington, D.C., where it currently is being subject to tests to determine the source of its deep-blue hue.
The exact color of the Hope Diamond has been the subject of some dispute. Jean-Baptiste Tavernier, the French explorer who is credited with the discovery and sale of the original 118-carat rough blue diamond from which the Hope emerged, and which subsequently was sold to King Louis XIV of France in 1668, described it as a "beautiful violet." In 1996, the GIA Gem Trade Lab was afforded the opportunity of examining the stone, and described it as fancy deep grayish blue.
Speaking to the New York Times, Jeffrey E. Post, a geologist and curator at the Smithsonian, said that the study of the Hope provides a window into more than one billion years of the Earth's history. "It sort of gets lumped into this category of being really a piece of jewelry, a cultural icon, a cursed gem, whatever," he said, adding: "It has a natural history that goes way beyond its human history."
In a recent article in the American Mineralogist, Dr. Post and his colleagues at the Smithsonian reported that the diamond contains surprisingly high levels of boron, more so than in many other blue diamonds that were studied.
The presence of boron in the diamond was not unexpected. Natural blue diamonds are known to contain the element, which also is the source of its orange-red fluorescence when viewed under an ultraviolet light source.
But where previous studies of blue diamonds reported levels of boron of less than one in a million, in parts of the Hope Diamond, boron levels were as high as eight per million atoms. In other parts of the stone hardly any boron was detected. Interestingly, though, the studies indicated that the concentration of boron did not necessarily influence the intensity of the blue color.
To study the Hope Diamond, the Smithsonian scientists placed it and 78 other blue diamonds in a device that fired gallium ions, which literally peeled off atoms from a patch about one fiftieth of a millimeter wide. The intention, of course, was to cause no perceptible damage to the diamonds.
The Smithsonian scientists plan to identify the type of boron in the diamond, and in so doing reveal its geological origin. One version of boron has a slightly heavier isotope, the result of an additional neutron. Rocks from the seafloor typically have more of the heavier boron than those found in the earth's mantle. According to Steven B. Shirey, a geochemist with the Carnegie Institution for Science in Washington, D.C., the boron in the Hope may have come from an ocean plate that was pushed downward near where the diamonds formed.
But to count the boron isotopes precisely, the Hope will have to be removed from its public display for longer than has been done as present. The problem is that the diamond is so popular among museum visitors that the Smithsonian has been reluctant to do that until now.
