Round Brilliant Cut Ratio

The ratio of a round brilliant cut diamond is the percentage of the length of each part relative to the average diameter of the girdle. The main evaluation indicators of diamond cut are: ratio (including table width ratio, crown height ratio, girdle thickness ratio, pavilion depth ratio, culet ratio, total depth ratio, star facet length ratio, lower girdle length ratio) and modification degree (including facet symmetry and polish quality). The ratio reflects the relative size and angle of the facets, which are the most important factors affecting brilliance. 

 The symmetry of the facets is the guarantee for the light to be reflected and refracted according to the designed facet angles, and poor symmetry will weaken the brightness. The finish of the facets, or the quality of the polish, can also significantly affect a diamond's brilliance. 

 (1) Table Size refers to the percentage of the table width relative to the average diameter of the girdle. The size of the table refers to the distance between the diagonals of the octagon of the table. 

 (2) Crown height ratio (Crown Height) The percentage of crown height relative to the average diameter of the girdle. Crown height is usually not measured directly, but the crown angle (crown angle) is used instead of crown height. 

(3) Girdle Thickness: The percentage of girdle thickness relative to the average diameter of the girdle. Waist thickness refers to the thickness of the narrowest part between the upper waist facet and the lower waist facet. There are 16 positions in total. Generally, the narrowest and widest areas are selected as the range of waist thickness. 

(4) Pavilion depth ratio (Pavilion Depth) The percentage of the height of the pavilion relative to the average diameter of the waist circumference. The height of the pavilion refers to the distance from the lower girdle to the bottom tip. 

(5) Culet Size: The percentage of the width of the bottom facet relative to the average diameter of the girdle. 

(6) Total Depth (Total Depth) is the percentage of the vertical distance from the culet to the table top and the average diameter of the waist. 

(7) Star facet length ratio (Star Facet Length) The percentage of the horizontal projection (ds) of the distance from the star facet vertex to the edge of the table relative to the horizontal projection (dc) of the distance from the edge of the table to the girdle edge. 

(8) Lower Girdle Facet Length (Lower Girdle Facet Length) The horizontal projection (dp) of the distance between the connection point of two adjacent pavilion main facets and the closest point on the girdle edge relative to the distance from the center of the culet to the girdle edge Percentage of horizontal projection (d1). 

 The ratio of each part is determined, and the relative size of each part and the angle of the main facet are determined. For example, the crown angle is determined by the crown height ratio and the table size ratio; the pavilion angle can be determined according to the pavilion depth ratio, and thus Determine the geometric shape of the round diamond wheel toilet to achieve the purpose of evaluating the round diamond ratio.