With a typical ratio between 1.33 and 1.66, the oval cut creates a bow-tie effect when light passes through the diamond. The central facets of the stone appear shadowed when this happens. Altering the depth of the pavilion and adjusting the angles of the table and facets causes light to diffuse in the central area.
Ratio is a crucial aspect to this shape as it may have a significant effect on both the light dispersion from within the stone and the appearance of the finger. When considering this shape, bear in mind that a longer shape with elongate the finger, while a rounded shape will help curb the bow-tie effect.