Cut  is  split  into  two  seperate  description, the  proportions  and position of facets.The correct  proportions  are important. For the best brilliance (lustre - dispersion, internal & external brilliance). The  correct  cutting  propertion are given  by  the  density  of  medium  the  diamond. Since begin of  this  century calculation  have  take  into  consideration. The optical-physical properties of diamond  - such  as  light  refraction, dispersion  and  hardness. To  achieve maximum brilliane trough suitable proportions and symmetry ratios.

Look under help page ideal cutting proportion.

By smaller size diamond, the impression at first sight, influenz. The judgment of the correct proportion, which are rarely checked - with years of experience and training, is enough for same goods.
For bigger size diamond the proportion must be tested for accurazy. The quality of the brilliance depend on
            Symmetry
            Proportion
            External features

1.  Symmetry - position of table and culet.
                          Size and regularity of the facets, girdle and culet.

2. Proportion - girdlediameter, table diameter, total height, thickness of girdle, crown height, pavilion depth, angle of crown facets, angle of pavilion facets.Look under help page ideal cutting proportion,look under help page ideal proportion