Black diamonds, also known as carbonadoes, are found primarily in central Africa and in Brazil. Black diamonds are impure polycrystalline diamonds that are composed of diamond, amorphous carbon and graphite.
Black diamonds are naturally black or dark gray in color and are more porous than other types of diamonds. The largest black diamond, as of 2015, was found in Brazil and is known as Sergio. It is 61 carats more than the heaviest clear diamond discovered. Unlike clear diamonds, black diamonds are opaque and consist of dense clusters of individual crystals. The dense clusters give the black diamond its dark color.