Last week at Sotheby’s Dubai, a 555.55 carat black diamond called “The Enigma ... exist in Brazil and the Central African Republic, “carbonado” black diamonds date from around 2.6 ...

Others maintain that carbon atoms (or, in a minority opinion, grains of meteoritic black graphite) within the hurtling meteorite ... The largest diamond ever found was a carbonado from Brazil ...

The gem is a carbonado, one of the toughest forms of natural diamond. Black diamonds are usually about 2.6 to 3.2 billion years old - a time before dinosaurs existed. The Earth itself is around 4. ...