gems, diamond, diamond prices, diamond grading, diamond cutting

The history of diamonds dates back more than two and a half thousand years. There is evidence for the use of diamond chips for industrial purposes—drilling beads and engraving other gems—by the middle of the first millennium BC, and comments by Indian and classical writers over succeeding centuries show that diamond crystals also had a value in ornaments. Diamond is the hardest known natural substance, with India long the only known source, and it is hardly surprising that the inability to cut or drill it contributed to its allure. It was the invincible stone, suitable for powerful men. Size and perfection of crystal shape were important criteria in assessing its desirability, but to these were added clarity, colour—in India different colours were suited to different castes, we are told—and, remarkably, what we would define as dispersion. This was the ability of a diamond to split the rays of the sun into a rainbow of light that could be projected onto walls and other flat surfaces, even onto a person’s face. Indian texts give quite specific details as to how this rainbow effect could best be observed.