Diamond Symmetry
The importance of symmetry in diamond grading
Diamond symmetry—an important aspect of a diamond's appearance, plays a crucial role in determining the overall quality and value of a diamond.
The symmetry of a diamond refers to the precision with which its various cut facets align and how well they interact with each other to produce a visually appealing gemstone.
Symmetry remains an important factor in diamond grading—a key part of the education provided by the Gemological Institute of America (GIA), one of the most respected and widely recognised authorities in the diamond industry.
GIA symmetry grades noted on diamond reports
Diamonds fall under the following grades applied to symmetry. The grade appears on the GIA report alongside other important information such as the cut, clarity, colour grade and clarity grade of the diamond.
Excellent Symmetry
Ranges from no symmetry features to minute symmetry features that can be viewed with difficulty face-up at 10 x magnification.
Very Good
Minor symmetry features are seen face up at 10 x magnification.
Good
Noticeable symmetry features are seen face-up at 10 x magnification. The Diamond’s overall appearance may be affected when viewed with the unaided eye.
Fair
Obvious symmetry features are seen face-up at 10 x magnification. The Diamond’s overall appearance is often affected when viewed with the unaided eye.
Poor
Prominent symmetry features are seen face-up at 10 x magnification. The Diamond’s overall appearance is significantly affected when viewed with the un aided eye.
How important is symmetry in a diamond?
The importance of diamond symmetry lies in the fact that it affects a diamond's brilliance, fire, and scintillation - three key factors that determine its visual appeal.
Brilliance refers to the amount of light that is reflected from a diamond's surface, while fire refers to the dispersion of light into the various colours of the rainbow. Scintillation describes the way in which light reflects off a diamond's surface as it is moved, creating a shimmering effect.
The symmetry of a diamond closely ties to these factors, as a well-cut diamond will maximize the amount of light that is reflected back to the observer, creating a more brilliant and dazzling appearance.
The GIA uses a specific system for evaluating diamond symmetry, which takes into account a number of factors, such as the alignment and placement of the diamond's facets, the overall balance of the stone, and the precision of its cut.
This system is based on the GIA's extensive research and experience in the diamond industry, and it is widely regarded as one of the most accurate and reliable methods for assessing diamond symmetry.
Angular Spectrum Evaluation Tool (ASET)
The GIA's system for evaluating diamond symmetry involves a detailed analysis of a diamond's cut using a variety of tools and techniques. One of the key tools used in this process is the ASET (Angular Spectrum Evaluation Tool), which measures the way in which light is reflected from a diamond's surface. This tool shows how well the diamond interacts with light and identifies areas of the stone that are unable to reflect light effectively. ASET photographs appear distinctive in red and green to visibly differentiate diamonds with better symmetry.
Use of an IdealScope
Another important tool used by the GIA is the IdealScope, which is used to evaluate a diamond's overall symmetry and balance. This tool creates a three-dimensional image of the diamond, which allows the evaluator to see how well the various facets of the stone are aligned and how well they are interacting with each other. By analyzing these images, the evaluator can determine whether the diamond is well-cut and symmetrical or whether there are any areas that need to be adjusted.
The GIA's system for evaluating diamond symmetry is an important part of the education provided by the institute, and it is widely used by diamond experts and retailers around the world. By understanding the importance of diamond symmetry and how it is evaluated, consumers can make more informed decisions when purchasing diamonds and can ensure that they are getting a high-quality stone that will look beautiful for years to come.
The AGS and other systems for symmetry
In addition to the GIA's system for evaluating diamond symmetry, there are also several other systems and standards that are used in the diamond industry. For example, the American Gem Society (AGS) has its own system for evaluating diamond cut quality, which takes into account a range of factors such as the diamond's proportions, symmetry, and polish. The AGS system is widely regarded as one of the most rigorous and accurate in the industry, and it is used by many high-end diamond retailers and manufacturers.