The Essentials You Need To Know When Purchasing and Caring For Your Diamond.
Diamond Cut

Symmetry

Symmetry and Polish determine the overall craftsmanship of the diamond, indicating the care and attention to detail by the cutter. Symmetry is the exactness of the diamond's shape, along with the symmetrical arrangement and even placement of its facets. There are two types of symmetry looked at when grading a diamond: proportional symmetry and facet symmetry.

Proportional symmetry is how well the table, crown, girdle, and pavilion align and work together. The grader carefully looks at the diamond from the top and side while checking that the table and culet are centered, the angles are consistent around the crown and pavilion, the table is flat, and the girdle is straight and of even thickness. Once they have an initial impression they move onto facet symmetry, to determine if the facets are formed well, are of equal size, meet at precise points and that the facets of the pavilion align with those on the crown. The grader also looks for extra facets, or ones that are missing from what is expected for that shape, as well as the presence of "naturals" or small portions of the original rough diamond that have not been polished. Symmetry is evaluated several times from different positions and then assigned a grade.

About Diamond Cut

The GIA Laboratory and most other labs assign a grade of Excellent, Very Good, Good, Fair or Poor, while the AGS Laboratory is unique in assigning a number of 0 through 10 with 0 being the best. A summary of the grades and what they mean is as follows:

  • GIA Excellent and AGS 0-1: No symmetry features or ones that are extremely or very difficult to see face-up at 10x magnification.
  • GIA Very Good and AGS 2-3: Symmetry features relatively easy to see face-up under 10x magnification but not visible with the unaided eye.
  • GIA Good and AGS 4-5-6: Symmetry features easy - very easy to see face-up under 10x magnification and difficult to see with the unaided eye.
  • GIA Fair and AGS 7-8: Obvious symmetry features when viewed face-up under 10x magnification. The diamond's appearance can be affected when viewed with the unaided eye.
  • GIA Poor and AGS 9-10: Prominent symmetry features when viewed face up at 10x magnification. The diamond's appearance is significantly affected when viewed with the unaided eye.

Although symmetry does not have as much impact as the proportions on the brilliance, fire and scintillation of the diamond, it is important to have the best symmetry possible to maximize the diamonds full potential.

Types of Symmetry Features

Culet Off-Center: The culet of the diamond is not centered in the pavilion. Culet Off-Center Table Off-Center: The table of the diamond is not centered in the crown. Table Off-Center
Extra Facet: An additional facet is present on the diamond that is not part of the standard design for that shape. Extra Facet Non-Pointing Facets: Facet's edges and corners do not meet precisely. Non=Pointing Facets
Misshapen Facets: Facets of the same type on the diamond have different shapes or sizes form one another. Misshapen Facets Misalignment: The crown and pavilion facets do not align at the girdle. Crown and Pavilion Alignment
Natural: Part of the original rough diamond is still present. Abrasion Non Octagonal Table: The table is not an octagon with equal angles, resulting in misshapen facets around the crown. Table Not Regular Octagon
Wavy Girdle: Girdle is not straight and appears wavy. Wavy Girdle Table and Girdle Not Parallel: The table is not parallel to the girdle of the diamond. Table and Girdle not Parallel