- carbonado, a natural diamond that is black in colour
- A black synthetic diamond, specifically a CVD polycrystalline diamond or HPHT polycrystalline compact diamond.
- boron carbide
- (South Africa, derogatory) A member of the new affluent black middle class in South Africa, characterised by conspicuous consumption.
- (skiing) A symbol representing a steep and relatively difficult trail, typically 40% gradient or above.
- (skiing): double black diamond
- ♦ (Unicode black diamond)