Rounded rectangular gemstone

Abstract

A rounded rectangular gemstone which comprises a crown provided with a planar table, a pavilion whose facets converge at a cutlet being disposed below said crown, and a girdle extending from said crown to said pavilion, said girdle being substantially perpendicular to said table and assuming a rectangular shape when viewed thereabove and therebelow, wherein said crown and said pavilion have substantially circular cross-sections along a plane parallel to said table and the facets of said pavilion are arranged in rotational symmetry about said cutlet and in mirror symmetry about lines of symmetry passing through said cutlet and the midpoint of each side of said girdle and through said cutlet and each corner of said girdle.

1 . A rounded rectangular gemstone comprising a crown provided with a planar table, a pavilion whose facets converge at a cutlet being disposed below said crown, and a girdle extending from said crown to said pavilion, said girdle being substantially perpendicular to said table and assuming a rectangular shape when viewed thereabove and therebelow, wherein said crown and said pavilion have substantially circular cross-sections along a plane parallel to said table and the facets of said pavilion are arranged in rotational symmetry about said cutlet and in mirror symmetry about lines of symmetry passing through said cutlet and the midpoint of each side of said girdle and through said cutlet and each corner of said girdle.  
   
   
       2 . The gemstone of  claim 1 , wherein the pavilion comprises: 
 a) a plurality of pavilion facets the lower edge of each converging at the cutlet, said plurality of pavilion facets comprising kite-shaped pavilion facets and shortened pavilion facets, the vertex of each of said kite-shaped pavilion facets extending from the corresponding corner of the girdle, whereby each of said kite-shaped pavilion facets is interspersed between a pair of said shortened pavilion facets and each of said shortened pavilion facets is interspersed between a pair of said kite-shaped pavilion facets, said kite-shaped and shortened pavilion facets arranged in rotational symmetry about said cutlet;    b) a plurality of lower hexagon facets arranged in such a way that a pair of lower hexagon facets is disposed between each pair of adjacent pavilion facets, each of said pair of lower hexagon facets comprising a larger and smaller facet, whereby said plurality of lower hexagon facets is provided with mirror symmetry about lines of symmetry passing through said cutlet and the midpoint of each side of the girdle and through said cutlet and each corner of the girdle; and    c) a plurality of hexagon facets, one side being collinear with the girdle, four sides being collinear with corresponding lower hexagon facets, and the remaining side being collinear with the end of said shortened pavilion facet.    
   
   
       3 . The gemstone of  claim 2 , wherein each of the hexagon pavilions is cut an angle ranging from 52-60 degrees, each of the lower hexagon facets is cut an angle ranging from 47-53 degrees, and each of the pavilion facets is cut an angle ranging from 39-44 degrees, with respect to the table.  
   
   
       4 . The gemstone of  claim 3 , wherein each of the hexagon pavilions is cut an angle of 55 degrees, each of the lower hexagon facets is cut an angle of 50 degrees, and each of the pavilion facets is cut an angle of 41 degrees, with respect to the table.  
   
   
       5 . The gemstone of  claim 2 , wherein the maximum depth of each hexagon facet ranges from 25-30 percent of the maximum girdle length and the minimum depth of each hexagon facet is 0 percent.  
   
   
       6 . The gemstone of  claim 5 , wherein the maximum depth of each hexagon facet is 27 percent of the maximum girdle length.  
   
   
       7 . The gemstone of  claim 2 , wherein the pavilion depth ranges from 72-83 percent of the maximum girdle length.  
   
   
       8 . The gemstone of  claim 7 , wherein the pavilion depth ranges from 77-78 percent of the maximum girdle length.  
   
   
       9 . The gemstone of  claim 2 , wherein 8 pavilion facets are employed, 16 lower hexagon facets are employed and 4 hexagon facets are employed.  
   
   
       10 . The gemstone of  claim 2 , wherein the crown comprises: 
 a) a plurality of triangular star facets, the long side of which is collinear with one side of the table;    b) a plurality of intermediate bezel facets, two sides of each of said intermediate bezel facets being collinear with the short side of two adjacent star facets and the remaining two sides converging to the midpoint of one side of the girdle;    c) a plurality of corner bezel facets, two short sides of each of said corner bezel facets being collinear with the short side of two adjacent star facets and the long sides converging to the corresponding corner of the girdle; and    d) a plurality of triangular upper girdle facets, the long side of each of said upper girdle facets being collinear with the girdle and one of the short sides being collinear with a short side of an adjacent upper girdle facets.    
   
   
       11 . The gemstone of  claim 10 , wherein each star facet is cut at angle ranging from 13-22 degrees, each intermediate and corner bezel facet is cut at an angle ranging from 27-40 degrees, and each upper girdle facet is cut at an angle ranging from 39-62 degrees, with respect to the table.  
   
   
       12 . The gemstone of  claim 11 , wherein each star facet is cut at an angle ranging from 15.0-19.5 degrees, each intermediate and corner bezel facet is cut at an angle ranging from 33.0-35.0 degrees and each upper girdle facet is cut at an angle ranging from 47-55 degrees with respect to the table.  
   
   
       13 . The gemstone of  claim 10 , wherein the vertex of each corner bezel facet that abuts each corresponding girdle corner defines a circle whose center is the projection of the cutlet onto the table, thereby providing radial symmetry.  
   
   
       14 . The gemstone of  claim 10 , wherein the vertex of each intermediate bezel facet that abuts the midpoint of the corresponding girdle side defines a circle whose center is the projection of the cutlet onto the table, thereby providing radial symmetry.  
   
   
       15 . The gemstone of  claim 10 , wherein 8 star facets, 4 intermediate bezel facets, 4 corner bezel facets and 16 upper girdle facets are employed.  
   
   
       16 . The gemstone of  claim 10 , wherein each hexagon facet is not projected onto a corner bezel facet.  
   
   
       17 . The gemstone of  claim 1 , wherein the girdle has a non-uniform height, the minimum height thereof ranging from 1-5 percent of the maximum girdle length and the maximum height thereof ranging from 10-20 percent of the maximum girdle length.  
   
   
       18 . The gemstone of  claim 1 , wherein each side of the girdle ranges from 86-94 degrees, with respect to the table.  
   
   
       19 . The gemstone of  claim 1 , wherein the ratio of maximum girdle length to minimum girdle length, when measured on a plane parallel to the table, ranges from 1-5.  
   
   
       20 . The gemstone of  claim 1 , wherein the table size ranges from 53-63 percent, and preferably at 58 percent, of the maximum girdle length.