Understanding ASET diamond imaging

If you spend a bit of time checking out different diamond jewelers' websites you will eventually come across an image called an ASET image.

How to Read A diamond ASET Image

These images are created by a small reflector tube that has colors painted on the inside. As the diamond gathers light it returns light from different angles from its surroundings.

As high quality diamonds are competing for the top spot the ASET tool is valuable for determining with great precision how much better one diamond is to another. Diamonds with above average fire and brilliance are highly prized. Since the level of brilliance is a little difficult to protray over the web the ASET is one of the best tools to show how a diamond is performing.

ASET =  Angular Spectrum Evaluation Tool.

The ASET was designed by experts at the American Gemological Society (AGS). The idea was to show clearly how a diamond handles light. ASET is now the tool that provides one of the most quantifiable results on diamond light performance. A jeweler or gemologist can use the ASET to demonstrate the light performance of a diamond. It's a great way of understanding the difference between different proportions.

ASET images

An example of several ASET images


ASET images are made up of the three colors that are reflected from the interior of the little ASET tube: red, blue, and green. These colors show how the light passing through a diamond is returned to the eye. Diamond facets have the amazing properties of acting as both windows and mirrors. Different angles of light collection by the diamond are shown in the image as different colors. The red color is the light collected from the higher angles, essentially the light collected from above. Green indicates returned light from lower angled light sources. Blue sections represent areas of contrast, these are the areas usually blocked by the head of the viewer which causes an effect called obscuration. As high contrast in diamond is seen to be a favorable trait strong blue arrows indicate that the diamond has good contrast.

ASET as a concept is not complicated. You look at a diamond through the top of a semi-sphere that has been painted with colors that mark the angular ranges. When the light is gathered by the diamond (instantaneously, by the way) the diamond has the different colors showing through the diamond. It will indicate areas of the diamond that are gather light from different angles as well as show the areas that are not  returning light.  This is called light leakage. Because light from different ranges above the horizon has different attributes, the ASET tool can provide important insight about how the diamond handles light. Easy? Good.