Fracture is the way a gem breaks when it does not split along a cleavage plane. Conchoidal fracture leaves curved, shell-like surfaces.
In more detail
Moissanite breaks with curved, shell-like fractures. A fracture is also the name for a crack inside a stone. In colored stones, labs often call such cracks fissures.
Related terms
- Cleavage: Cleavage is a mineral's tendency to split along flat planes in its crystal structure. A hard knock in a cleavage direction can split a stone.
- Toughness: Toughness is a gem's resistance to chipping and breaking. It differs from hardness, which is resistance to scratching.
- Fissure: A fissure is a crack in a gem, often open to the surface. Labs use the word for the cracks that fillers can enter.
- Durability: Durability is a gem's ability to resist scratching, breaking, and damage from heat, light or chemicals. It has three parts: hardness, toughness and stability.