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ASET: Angular Spectrum Evaluation Tool

The key to choosing your forever stone is by carefully reviewing and understanding its cut quality and light performance; referring specifically to the diamond’s fire and brilliance. The best way to do so is through an ingenious device called the ASET.


What Is ASET?

The Angular Spectrum Evaluation Tool, more commonly known in the industry as ‘ASET’ is a device created by the American Gemological Society (AGS).  The AGS ASET is a scientific tool that shows where a diamond collects light in the hemisphere above, and whether that light properly returns to the viewer’s eyes, or leaks-through and is lost. It allows for a large quantity of information to be gathered in a relatively simple manner; of which is then passed onto you through your diamond retailer, predominantly through your diamond certification.

How Does It Work?

As mentioned above, by viewing a diamond from the top of a hemisphere (painted with different colours to delineate specific angular ranges) the light will appear in different colours depending on where that light is coming from. It will also indicate areas of the diamond that may not be returning light, commonly referred to as ‘light leakage’.

The views that the ASET produces of a well-cut ‘round brilliant’ diamond will show a preponderance of red, minuscule flecks of green, a symmetrical pattern of blue and extremely low light leakage, as seen in the image below.


By providing you with Crafted by Infinity, ‘High Performance’ diamonds, we can guarantee that with each diamond you will receive a pattern of crisp, precise blue from the lowest eight facets, boosting sharp ‘on-off’ sparkle, an abundance of red promoting intense brightness and symmetrical small flecks of green showing side brightness. All this wrapped with a promise of there being absolutely no black areas of light-leakage.

 ASET Devices

There are several different versions of the ASET tool. There are handheld and desktop models as well as many different improvised photo setups. There are backlit versions and versions with dark background; the former will show leakage as white, the latter will show leakage as black.

We at Durham Rose, use the Crafted by Infinity ‘Infinity Viewer’ which allows for three separate inspections to be conducted to ensure the highest possible assessment is done.

Why Is It Important?

ASET based analysis holds many strengths but, but a surprising element is that it can be applied to ANY shape diamond. AGS now have grading systems for Round, Princess, Oval, Emerald Cut, and certain Cushion stone shapes. It should be noted that ‘Fancy’ shaped diamonds have variable ASET signatures; however, through using an ASET assessment, it can provide the client with an insight into how the diamond is performing in relation to its light performance and more importantly, leakage and how that can impact on the value of your diamond. Through the process of procurement to delivering it safely to your loved one, the ASET enables us at Durham Rose to give you the best technical understanding, value for money and reassurance that your forever piece has been made with the utmost attention to every detail. See more on how we select diamonds here.


Allow us to help you in selecting only the finest, light performing, best value diamond for your custom diamond engagement ring. Speak with one of our diamond experts today.

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