Abstract: A gemstone is provided that has an improved brilliance, especially at the crown portion of the gemstone. The gemstone has a crown angle that is less than an ideal cut round diamond and, preferably the crown angle is less than 27 degrees. By reducing the crown angle of the gemstone, light entering one end of the crown portion may exit the opposite end of the gemstone. In addition, reducing the crown angle reduces the mass necessary for the gemstone. As a result, the gemstone has a width or diameter that corresponds to a larger mass gemstone that is cut according to conventional ideal proportions.

Abstract: A square princess cut gemstone (100) comprises a crown (300) having thirteen facets (310, 321-324, 331-334, 345-348). The crown facets include a square table facet (310) forming the top of the crown's truncated pyramid shape. Four upper girdle facets (321-324) extend upward from girdle edges (231-234). Four table-surrounding facets (331-334) extend upward from the upper girdle facets (321-324) to the table facet (310). Four bezel facets (345-348) straddles at least one of the adjoining corners of the upper girdle facets (321-324) and the adjoining corners of the table-surrounding facets (331-334).

Abstract: A square princess cut gemstone (100) comprises a crown (300) having thirteen facets (310, 321-324, 331-334, 345-348). The crown facets include a square table facet (310) forming the top of the crown's truncated pyramid shape. Four upper girdle facets (321-324) extend upward from girdle edges (231-234). Four table-surrounding facets (331-334) extend upward from the upper girdle facets (321-324) to the table facet (310). Four bezel facets (345-348) straddles at least one of the adjoining corners of the upper girdle facets (321-324) and the adjoining corners of the table-surrounding facets (331-334).

Abstract: A circular cut diamond (10) comprising a girdle (20), a crown (30), and a pavilion (40). The crown (30) comprises a circumferential succession of eight main crown facets which extend upward from an upper edge (23) of the girdle at a crown angle which is greater than 19° and less than 25°. The pavilion (40) comprises a circumferential succession of eight main pavilion facets which extend downward from a lower edge (24) of the girdle at a pavilion angle which is greater than 41° and less than 43°. The circular cut diamond (10) can compete with the brilliance of an ideal cut diamond without a significant compromise in carat weight.

Abstract: A circular cut diamond (10) comprising a girdle (20), a crown (30), and a pavilion (40). The crown (30) comprises a circumferential succession of eight main crown facets which extend upward from an upper edge (23) of the girdle at a crown angle which is greater than 19° and less than 25°. The pavilion (40) comprises a circumferential succession of eight main pavilion facets which extend downward from a lower edge (24) of the girdle at a pavilion angle which is greater than 41° and less than 43°. The circular cut diamond (10) can compete with the brilliance of an ideal cut diamond without a significant compromise in carat weight.

Abstract: A gemstone is provided that has an improved brilliance, especially at the crown portion of the gemstone. The gemstone has a crown angle that is less than an ideal cut round diamond and, preferably the crown angle is less than 27 degrees. By reducing the crown angle of the gemstone, light entering one end of the crown portion may exit the opposite end of the gemstone. In addition, reducing the crown angle reduces the mass necessary for the gemstone. As a result, the gemstone has a width or diameter that corresponds to a larger mass gemstone that is cut according to conventional ideal proportions.