Diamond Rough out of the mine, a diamond pre-polished and cut looks like this.
created at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle.
the hardest natural material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the Mohs scale of mineral hardness. Diamond has a hardness of 10 (hardest) on this scale.
diamond hardness depends on its purity (the absence of any other elements), crystalline perfection and orientation.
diamonds come in many colours.