What causes cleavage in diamonds?

Cleavage in diamonds is primarily caused by the arrangement of carbon atoms within the crystal structure. Diamonds possess a specific type of atomic bonding, with the carbon atoms arranged in a tetrahedral lattice. This arrangement results in planes of weakness within the crystal.

When there are wide spaces between these atomic planes, it allows for the separation of these layers, leading to cleavage when the diamond is subjected to stress or impact. The presence of these wide spaces creates a directional weakness along specific planes, which is why diamonds can cleave cleanly in certain directions.

In contrast, narrow spaces would not provide the same conditions for cleavage. Heat exposure and pressure from external forces may affect a diamond's integrity, but they do not directly cause the characteristic cleaving that occurs along specific structural planes in the crystal.