Diamond Properties : Durability

Durability is the degree to which materials withstand the destructive effect of the conditions to which they are subjected. Hardness is not the only measure of a mineral's durability--the relative resistance to fracture is another. Although diamond is not fragile or prone to breaking apart, all substances including diamond can fracture or shatter. Due to its particular crystal structure, diamond has certain planes of weakness along which it can be split.

Diamond is said to have perfect cleavage in four different directions, meaning it will separate neatly along these lines rather than in a jagged or irregular fashion. This is because the diamond crystal has fewer chemical bonds along the plane of its octahedral face than in other directions. Diamond cutters take advantage of cleavage to fashion diamonds efficiently.

Hardness 10 on Mohs scale. The hardest natural substance. Diamonds can be cut and polished only with other diamonds, and only because of slight directional differences in hardness and a perfect octahedral cleavage. While diamonds are tough, they can be chipped along sharp girdles or facet edges.

Diamonds are also highly heat resistant, but they can be burned if subjected to prolonged high heat. This sometimes happens when platinum prongs are retipped by jewelers unfamiliar with the high melting point of platinum; repolishing usually results in minimal weight loss.

Almost all diamonds have some inclusions and the intensity of these are described on a scale that ranges from Flawless (FL) and Internally Flawless (IF) to Imperfect to the third degree (I3). An I3 diamond has major inclusions that are so severe they may threaten the diamond's durability SI1 Slight inclusions which do not affect the diamond's durability and are visible under 10 power. SI2 Slight inclusions which do not affect the diamond's durability. Some inclusions may be visible to the unaided eye.

Other Properties of Diamond.