The cut of a diamond refers to the proportions of the diamond, depending on its shape. Ideal cut dictates that every facet be placed at exact angles and proportions that create the ideal balance between maximum brilliance and dispersion (Prism Effect). Proper cutting and proportioning alone release the full beauty of a diamond. These affect its durability and directly influence its price. The story began in 1919, when the Belgian mathematician Marcel Tolkowsky published his findings, 'Diamond Design', in London. He based his calculations on the modern theories of light behavior. His work came to be known today as the 'Ideal Cut' .   TABLE The large flat facet located at the top of the diamond. CROWN The top half of a diamond controls it’s fire, which is the dispersion of prismatic color that emerges from a diamond. PAVILION The bottom half of a diamond controls it’s brilliance - the white light. GIRDLE The diamond's edge that is beneath the crown and stand above the pavilion culet: is the small facet located at the bottom of a diamond and tapers off what would otherwise be a sharp and brittle point.   An ideal cut diamond is a round briliant cut diamond, within the proportions as defined here: Table diameter:  53% to 57% Crown angle:  33.7° to 35.0° Pavilion depth:  42.5% to 43.8% Girdle thickness:  thin, medium, slightly thick. Culet size:  none, pointed, very small, small, and medium.