Black diamond, also referred to as carbonado, is one of the hardest varieties of natural diamond. Diamond, graphite, and amorphous carbon are all present in this impure, high-density, micro-porous type of polycrystalline diamond, along with sporadic reduced metal inclusions and tiny crystalline precipitates that fill the pores. As fancy coloured diamonds, black diamonds are graded differently from more prevalent white or colourless diamonds. Black diamonds may be less expensive than white diamonds than other fancy colours, such as blues or pinks, because there is less demand for them.
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