The cut is a reference to the proportions, symmetry, polish, and shape of a diamond. It is the cut of a diamond that will influence the diamond’s reflective character and value. This is the extent to which a diamond will reflect light from within itself, from one mirror-like facet to another, and then disperse it through the top of the stone, known as a diamonds “brilliance”.
A diamond with well-cut angles (symmetry) and a good finish will enhance the diamond’s light and brilliance. In a well-cut diamond, light enters through the table and travels to the pavilion where it is reflected from one side to the other before being reflected out of the diamond through the table. A well-cut diamond will reflect all of the light back causing the stunning brilliance that
makes diamonds so alluring.
Despite the minor differences between the various grading systems the following different cut grade descriptions are broadly accepted by the diamond industry:
IDEAL CUT diamonds maximize the brilliance that is reflected out of the table of a diamond. This maximum brilliance is achieved through the exact calculation of the symmetry and proportions of the diamond. When finished with the highest standards in polishing of the surface of the stone, these diamonds become the best available.
EXCELLENT CUT generally also display maximum brilliance, however, they are not as exacting in terms of their symmetry and proportions.
VERY GOOD CUT is when most of the light that enters the diamond will be reflected back through the table, creating a high amount of brilliance. A very good cut diamond may have a table size or girdle width that does not comply with an ideal cut or excellent cut diamonds. However, in many instances, very good cut diamonds will possess symmetry and proportion characteristics that overlap with those of ideal cut and excellent cut diamonds. These diamonds provide a very good value purchase for buyers seeking a slightly larger diamond for
the same price as ideal cut and excellent cut diamonds.
GOOD CUT diamonds reflect much of the light that enters them back through the table.
In such diamonds, the craftsmen have significantly deviated from the proportions of ideal cut and excellent cut diamonds to create the largest possible diamond from the original rough crystal diamond. These diamonds may provide the option of a larger diamond then a very good cut diamond for the same price.
FAIR & POOR CUT only reflect a small amount of the light that enters, back through the table. Most usually these diamonds have been cut where maximum carat weight was the most important criteria.