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 (

High Performance

Medium Performance

Low Performance

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Designer Jewels, Inc. is a Houston fine jewelry designer providing jewelry appraisal services, custom design and repair. We provide lapidary services as well. We also buy and sell old estate jewelry.