Diamond appraisals in Houston provided by Bob and Mark Sandler, certified gemologists.
In order to grade a mounted diamond for performance, according to AGS Standards, we use the Angular Spectrum Evaluation Tool (ASET®) and ASET® Image Comparison Charts to assess performance. The ASET image provides a quick and easy way to assess a diamond’s interaction with light. It’s brightness, leakage, and contrast can be evaluated by noting the pattern and amount of red, blue, green, and black.
RED: Light collected from the optimal angles. The light which diamond uses most effectively. It represents brightness and optical efficiency.
GREEN: Light collected from less than optimal angles and which is less efficient.
BLUE: Represents "Contrast" or "Optical Texture". Caused by light being obscured by the viewer's head and torso & creates light and dark areas. Demonstrates balance & symmetry.
BLACK: (or White, depending upon which ASET too is used): This represents "Leakage", light that is literally lost.*
The ASET® Image Comparison Charts are listed below for high, medium and low performance.
* Content and Charts provided by American Gem Society (www.americangemsociety.org)
High Performance
Medium Performance