The luminosity of a diamond is determined by its cut. When the 58 facets and pavilion depth of a stone are cut with precision, it allows light to disperse through its crown in an explosion of brilliance. While the cut of a diamond affects its brightness, fire and scintillation, it also defines its shape. While the round diamond is a classic-cut, princess, marquise, oval, pear, heart and emerald cuts are equally popular.