One of the most defining characteristics of a diamond is its cut. While high grades of color, clarity, and carat weight also contribute to a diamond's appeal, it's the cut that determines the symmetry of the stone's facets, its overall proportions, and its ability to reflect light. An expertly cut diamond will achieve high levels of brilliance, sparkle, and durability. Even if a diamond is graded well in other areas, a poor cut can result in a dull, muted effect.