facets and greater fire at the expense of brilliance) or too large (resulting in smaller crown facets and little to no fire). Polish and symmetry Polish and symmetry are two important aspects of the cut. The polish describes the smoothness of the diamond's facets, and the symmetry refers to alignment of the facets. With poor polish, the surface of a facet may be scratched or dulled, and may cause a blurred or dulled sparkle. While most polish defects are a result of the cutting process, some surface flaws are a result of defects in the natural stone. One example is grain lines (produced when irregular crystallization occurs as a diamond is formed) running across the facet. Severe polish defects may cause the diamond to constantly look like it needs to be cleaned. With poor symmetry, light can be misdirected as it enters and exits the diamond. Choice of cut The choice of diamond cut is often decided by the original shape of the rough stone, location of internal flaws or inclusions, the preservation of carat weight, and popularity of certain shapes among consumers. The cutter must consider each of these variables before proceeding. Most gem-quality diamond crystals are octahedra in their rough state (see material properties of diamond). These crystals are usually cut into round brilliants because it is possible to cut two such stones out of one octahedron with minimal loss of weight. If the crystal is malformed or twinned, or if inclusions are present at inopportune locations, the diamond is more likely to receive a fancy cut (a cut other than a round brilliant). This is especially true in the case of macle, which are flattened twin octahedron crystals. Round brilliants have certain requisite proportions that would result in high weight loss, whereas fancy cuts are typically much more flexible in this regard. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve carat weight, since the per-carat price of diamond is much higher when the stone is over one carat (200 mg). While the round brilliant cut is considered standard for diamond, with its shape and proportions nearly constant, the choice of fancy cut is influenced heavily by fashion. For example, the step cut baguette—which accentuates a diamond's luster, whiteness, and clarity but downplays its fire—was all the rage during the Art Deco period, whereas the mixed Princess cut—which