The proportions of a diamond cut can greatly affect the way that light bounces around the stone. Each cut of diamond has a threshold of ideal angles and proportions that ensure the maximum return of light and brilliance of the stone. Diamonds that are cut out of the ideal proportions can lose light through the back facets or in the figure of the viewer, and so can appear dull and lifeless. The more symmetry within the faceted diamond, the greater the return of light and sparkle. The polish is judged by the stones freedom from scratches, lines or burn marks caused during the polishing process.