BACKGROUND: The origin of carbonado -- more popularly known as black diamond -- have long been a mystery to scientists. New analysis of the world's toughest diamonds suggests they might have come from outer space, specifically from a star that exploded long ago, called a supernova. Researchers from Florida International University believe carbonados came from a large, diamond-bearing asteroid that may have fallen to earth billions of years ago, when the earth and moon were being heavily bombarded by space rocks.
ABOUT CARBONADO: The term "carbonado" was coined by Portuguese in Brazil in the mid 18th century because it resembles porous charcoal. Carbonado diamonds are so tough that it took a 20-ton hydraulic press to break one. This means it is almost impossible to work carbonado into jewelry settings, since they are too hard to be polished or cut -- except with another carbonado. They get their hardness from their structure. While conventional diamonds are cut from a single crystal that breaks easily along a natural line, carbonados are made of millions of small crystals stuck together. Carbonados were first used to polish Brazilian hardwood before transporting it to Europe. In 1905 it was used to drill the rocks for the Panama Canal.
HOW DIAMONDS FORM: Conventional diamonds are formed deep in the earth, since the carbon requires intense heat and pressure to form diamond. Thanks to a series of volcanic eruptions between 1 billion and 100 million years ago, the diamonds came to the surface, where they can be mined. But carbonado is much older -- as much as 3.8 billion years -- and is found only in Brazil and the Central African Republic. The Florida researchers used infrared synchrotron radiation at Brookhaven National Laboratory to identify very tiny amounts of other elements in carbonado. They found hydrogen, which indicates an origin in hydrogen-rich interstellar space. They believe that carbonado diamonds formed in stellar supernova explosions, which formed large asteroids that traveled through space before landing on earth some 2.3 billion years ago.
The American Astronomical Society, the American Geophysical Unionand the Materials Research Society contributed to the information contained in the TV portion of this report.