Lonsdaleite static press or using explosives. It has also been produced by chemical vapor deposition, and also by the thermal decomposition of a polymer, poly(hydridocarbyne), at atmospheric pressure, under argon atmosphere, at . It is translucent, brownish-yellow, and has an index of refraction of 2.40 to 2.41 and a specific gravity of 3.2 to 3.3. Its hardness is theoretically superior to that of cubic diamond (up to 58% more), according to computational simulations, but natural specimens exhibited somewhat lower hardness through a large range of values (from 7 to 8 on Mohs hardness scale). The cause is speculated as being due
Tension ring a tension setting safely: diamonds, rubies, moissanite, and sapphires. Additionally, tension setting manufacturers must be careful which stones they place in tension settings; a stone that either has significant inclusions or is too soft will fracture under the intense pressure of the setting. The Mohs scale is a reliable way to rank a gem's hardness; generally gems that have a Mohs hardness of less than 9.0 cannot be placed in the setting. It should also be noted that the term "tension setting" is, from the perspective of physical science, a misnomer. The stone is not held in tension (a pulling