Round cut gemstone exhibiting excellent optical brilliance

Abstract

A gemstone including a substantially round girdle, a crown extending in a first direction from the girdle, and a pavilion extending in a second direction from the girdle opposite the first direction. The gemstone has 73 uniquely arranged and angled facets, 33 of which are in the crown, and 40 of which are in the pavilion. The height of the crown is preferably between 12.5 to 19.5% of the diameter of the stone, the total depth of the stone is preferably between 59-62.9% of the diameter of the stone, the depth of the pavilion is between 42.9 to 44.5% of the diameter of the stone, and the diameter of the table is preferably between 53-60% of the diameter of the stone.

What is claimed is: 
     
         1 . A gemstone comprising:
 a substantially round girdle;   a crown extending in a first direction from the girdle, the crown having a table, eight main facets surrounding the table, eight star facets positioned between adjacent facets of the eight main facets and the table, and sixteen top half facets, wherein a respective pair of the sixteen top-half facets are positioned between the adjacent facets of the eight main facets and the girdle; and   a pavilion extending in a second direction from the girdle, opposite the first direction, the pavilion having eight main pavilion facets each of which extend from the girdle to a bottom of the pavilion, sixteen upper half facets, and sixteen lower half facets, wherein a respective pair of the sixteen upper half facets are positioned between adjacent facets of the eight main pavilion facets and the girdle, and a respective pair of the sixteen lower half facets are positioned between adjacent facets of the sixteen upper half facets and the girdle, wherein   the eight main facets are at an angle of approximately 32-36° relative to a first plane parallel to a surface of the table,   the eight star facets are at an angle of approximately 22-26° relative to the first plane,   the sixteen top-half facets are at an angle of approximately 39-44° relative to the first plane,   the eight main pavilion facets are each at an angle of approximately 40.6-41.4° relative to a second plane parallel to a face of the girdle,   the sixteen upper half facets are each at an angle of approximately 41.4-42° relative to the second plane, and   the sixteen lower half facets are each at an angle of approximately 42-42.9° relative to the second plane.   
     
     
         2 . The gemstone according to  claim 1 , wherein each of the eight star facets defines a respective side of the table. 
     
     
         3 . The gemstone according to  claim 1 , wherein a height of the crown is between 12.5 to 19.5% of a diameter of the gemstone. 
     
     
         4 . The gemstone according to  claim 1 , wherein a depth of the gemstone is between 59-62.9% of a diameter of the gemstone. 
     
     
         5 . The gemstone according to  claim 1 , wherein a depth of the pavilion is between 42.9 to 44.5% of a diameter of the gemstone. 
     
     
         6 . The gemstone according to  claim 1 , wherein a diameter of the table is between 53-60% of the width of the gemstone, 
     
     
         7 . The gemstone according to  claim 1 , wherein a thickness of the girdle is 1% to 7% of a diameter of the gemstone. 
     
     
         8 . The gemstone according to  claim 1 , wherein the bottom of the pavilion is a culet. 
     
     
         9 . The gemstone according to  claim 8 , wherein the culet has an area of 3% or less of the diameter of the gemstone. 
     
     
         10 . The gemstone according to  claim 1 , wherein the gemstone has an average 96% light performance characteristic. 
     
     
         11 . The gemstone according to  claim 1 , wherein:
 a height of the crown is between 12.5 to 19.5% of a diameter of the gemstone,   a depth of the gemstone is between 59-62.9% of the diameter of the gemstone,   a depth of the pavilion is between 42.9 to 44.5% of the diameter of the gemstone, and   a diameter of the table is between 53-60% of the width of the gemstone.