Numerical Method on Inclination of Star Facet,Upper and Lower Girdle Facets of Round Brilliant Cut

It is quite important for calculating precisely inclination of star facet,upper girdle and lower girdle facets during gem processing. The numerical relations between the inclination of star facet,upper and lower girdle facets and cut parameters including crown angle,table proportion,star facet length proportion,lower girdle facet length proportion and pavilion angle are analysed and calculated by the geometry method,abtaining the precise calculating methods and parameters.