Despite its exceptional hardness, a diamond under the influence of a strong impact easily splits along planes parallel to the faces of a regular octahedron. This property of a diamond is used to give the stones a certain shape even before they are cut and polished. Diamonds that are absolutely transparent and free from flaws are said to be "pure water". Such diamonds, when they do not possess any color shade, with the exception of bluish, are valued most highly. Stones with a faint yellowish ...