The diamond consists in a crystal lattice of carbon atoms arranged in an octahedral structure. It was discovered for the first time in India, that remained the only available source until the eighteen century. Its name is mentioned for the first time in a book only discovered around 1905, by an Indian politician and philosopher who lived in 300 B.C. Already at those times, diamonds belonged "de jure" to the ruling family, especially those with a perfect octahedral shape, and they were not exported, unlike the other precious stones that were exported instead. The diamond fascinated not only for its beauty, but also for its toughness, higher than any other precious stone. As a matter of fact, its name comes from the Greek "Adamas", the invincible.