Natural black diamonds are rare and have a deep, opaque black color due to inclusions of graphite, carbon, or hematite. Black Diamonds have a metallic luster and can sometimes appear slightly translucent in certain lighting. Like all diamonds, black diamonds rank 10 on the Mohs hardness scale, making them one of the hardest substances known. Beads are often faceted to enhance their sparkle, but they can also be found in smooth, round, or raw nugget forms.
Some people believe black diamonds have grounding and protective energies.