A mixture of carbon allotropes in which the carbon-carbon bonds are carefully arranged through nanoscale mechanochemistry to confer greater hardness, toughness, and flexibility than that of standard diamondoid. The greatest strength of crystalline diamond is also its greatest weakness; the regular structure makes it brittle, prone to fracture along cleavage planes. By including microcrystals of other carbon allotropes such as lonsdaleite and carbon nanotube within its diamond matrix, adamant is optimised for maximum durability.
Although it is more expensive than ordinary diamondoid, adamant is popular as a building material for specialty applications such as the creation of ship hulls. Unlike diamondoid, which may be tailored to various degrees of colour and transparency, fully optimized adamant is an austere grey, though it does have a high diamond-like lustre.