This allows all the light entering from any direction to be totally reflected through the top and dispersed into a gorgeous display of color. Even until recent years little importance was attached to the quality of the cut. Before that time, grading was restricted solely to color and clarity. Until the beginning of 20th century, the forms of diamond cuts developed through trial and error as the optimal brilliance effect was pursued. Only since 1910 have calculations been employed which consider the optical and physical properties of diamond - such as hardness, light refraction and dispersion, in order to achieve maximum brilliance through correct proportions and symmetry.
Uncut diamonds hide the unique optical properties of the cut stones.
Rough diamonds have a yellow, brown, or grey non-transparent skin which covers them. Only cutting can transform the unattractive 'pebble' into that crystal clear stone which, in clarity, luster and play of color surpasses all other precious stones. Most of the beauty of a cut diamond is in its amazing optical properties, particularly in the way it bends light, and its play of color. The round brilliant displays these properties in the cut state where all of the factors blend in optical harmony with one another to create the highest degree of brilliance. Color and Clarity are rarity factors given to us by nature.