Diamond cubic strong isotropic property. Namely, for any two vertices "x" and "y" of the crystal net, and for any ordering of the edges adjacent to "x" and any ordering of the edges adjacent to "y", there is a net-preserving congruence taking "x" to "y" and each "x"-edge to the similarly ordered "y"-edge. Another (hypothetical) crystal with this property is the Laves graph (also called the K crystal, (10,3)-a, or the diamond twin). The compressive strength and hardness of diamond and various other materials, such as boron nitride, is attributed to the diamond cubic structure. Similarly truss systems that follow the diamond
Centenary Diamond initial efforts were done by head rather than with a hand or saw so as not to heat or vibrate the diamond. After cutting and removing of cracked material over 154 days, the team was left with an egg-shaped gem of approximately . Thirteen different designs were presented to the De Beers board, with a strong recommendation for what became the eventual modified heart-shaped design. The shape was described as, "Effectively, the Centenary Diamond is shaped like a heart-shape, but it does not have a groove. The image the team had in mind was a shape which would adorn the