Using ASET to Judge Light Performance in Emerald Cut Diamonds

One look at the ASET images of these four emerald cut diamonds, and you know that the Brian Gavin Signature Emerald on the left is brighter and better looking.

It's easy to see that colors reflected by the ASET Scope are bolder, brighter, and distributed more evenly, right? It doesn’t take a rocket scientist to know that when it comes to diamonds, brighter is better.

The American Gem Society Laboratory developed Angular Spectrum Evaluation Technology (ASET) to enable you to quickly and easily determine which diamond exhibits better light performance. As you can see, that’s pretty easy to figure out. However, you might be wondering about the principle behind the ASET Scope, and what each of those colors represents.

The Working Principles of ASET:

ASET works on the principle that we live in a hemisphere where the sun illuminates the earth from different positions throughout the day. Depending on your proximity to the sun, the light which illuminates our lives will be brighter, or less intense, and create shadows.

With that in mind, tell me what is brighter: The intensity of light at sunrise, sunset, or mid-day? You might be inclined to say mid-day because that is when the sun feels hotter. However, keep in mind that the distance between the earth and the sun remains relatively constant.

Therefore, what affects our interpretation of that light, is the direction from where it comes and the contrast which the shadows create. The differences in how light reflects off the facets of a diamond create depth of field, which enables us to appreciate the subtle differences in intensity.

ASET Scope Colors for Emerald Cut Diamonds:

As you can see, the ASET Scope held by Brian Gavin to the left uses different colors to distinguish where a diamond is gathering light.

The color green represents low-intensity light that occurs in the 45-degree region of the hemisphere. The type of light that you see when the sun is rising or setting is low-intensity light.

The light that is visible in the next 35-degrees of the hemisphere is more intense. The reddish-orange color that you see on the ASET Scope represents more intense light reflecting within the diamond.

The color blue on an ASET Scope represents the lighting effects created by the position of the midday sun being over our heads. The location of the sun at that time of day produces shadows and contrast as objects block the light shining down from above.

It is that contrast that shows up as blue on an ASET Scope image. However, contrast shows up as black in clarity photographs and video because the main pavilion facets are reflecting the dark color of the camera lens instead of the blue color on the ASET Scope.

Interpreting ASET Scope Images for Emerald Cut Diamonds:

At first glance, it may seem more straightforward to interpret ASET Scope images for round brilliant cut diamonds because the light appears to reflect in a more symmetrical pattern.

At the same time, the basic principles that each color represents in an ASET Scope image remain constant regardless of diamond shape or size. Light enters the ASET from different directions and reflects off the facets of diamonds in the same fashion.

Therefore the transition from using ASET to evaluate the light performance of round and fancy shape diamonds is relatively painless. The idea is to focus on the pattern of light reflecting throughout the diamond and look for high intensity of reds and greens with proper distribution and contrast.

With that principle in mind, the ASET Scope images for the two emerald cut diamonds above might seem pretty good. Afterall, there is a lot of reds and greens which appear to be relatively even in distribution and intensity.

The truth is that these emerald cut diamonds exhibit better than most. However, the reality is that the light return of Brian Gavin Signature Emerald cut diamonds is even better. The reason is simple, just look at all that black that is evident under the table facet.

Using ASET to Select a Brighter Emerald cut diamond:

Take a look at the ASET images for the two Brian Gavin Signature emerald cut diamonds above. What do you see? A higher concentration of red, which represents the brightest light available from within the hemisphere.

The black region visible along the table facet in the last pair of ASET images shows bright red with high contrast (blue) in these diamonds. That means that these Brian Gavin Signature Emerald cut diamonds are going to show an even higher level of brightness.

One thing to keep in mind as you review ASET Scope images for emerald cut diamonds is that it is not as straightforward as it is with round diamonds. A round brilliant cut diamond features 58 facets including the culet, which the diamond cutter indexes upon the surface evenly in sections of eight.

Whereas emerald cut diamonds are rectangular and each diamond varies in length and width. With that in mind, the pattern of colors reflecting throughout the diamond as seen through an ASET Scope are going to differ from one stone to another.

Therefore what you should look for is an emerald cut diamond that exhibits a lot of red under the table facet, with sharp contrast (blue) and secondary brightness in the form of green.

It is entirely reasonable for there to be some black in the four corners of the diamond and along the outer edge. Thankfully a little bit of black in those regions seems to be of no consequence as far as the eyes can see.

Once again, what you're looking for is a reasonable amount of consistency in the distribution of the colors reflecting throughout the diamond as seen through an ASET Scope.

In light of this new understanding of how you can use ASET Scope images to select a brighter looking emerald cut diamond, I'm sure you'll enjoy they symphony of brilliance visible within every Brian Gavin Signature Emerald cut diamond.