Jan 22nd, 2013

Is it a bird?

The Raven is a 12.78 carat black trilliant shape purchased in 2011. It is currently in a private collection in upstate NY.

Carbonado, commonly known as the “Black Diamond”, is a natural polycrystalline diamond found in alluvial deposits in the
Central African Republic and Brazil. Its natural colour ranges from black to dark grey, and it is more porous than other diamonds.

There are some supporters of an extraterrestrial origin of carbonados, such as Dr. Stephen Haggerty, a geo-scientist from Florida International University, who have propose that their material source was a supernova which occurred at least 3.8 billion years ago. After coalescing and drifting through outer space for about one and a half billion years, a large mass fell to earth as a meteor approximately 2.3 billion years ago, possibly fragmenting during entry into the Earth’s atmosphere, and impacting in a region which would much later split into Brazil and the Central African Republic, the only two known locations of carbonado deposits.

Some of the other theories of  origin of carbonados are also quite controversial.

Some proposed hypotheses are as follows:

Direct conversion of organic carbon under high-pressure conditions in the Earth’s interior, the most common hypothesis for diamond formation;

Shock metamorphism induced by meteoric impact at the Earth’s surface;

Radiation-induced diamond formation by spontaneous fission of uranium and thorium; and

Formation inside an earlier-generation giant star in our area, that long ago exploded in a supernova.

Needless to say, none of these hypotheses for carbonado formation had come into wide acceptance in the scientific literature by 2008.

Source

Wikipedia