How to read ASET for a princess cut diamond
“I’m shopping for a princess cut diamond engagement ring and a friend recommended me to your site, he purchased a Brian Gavin Signature round diamond about a year ago. The diamond he bought truly is stunning and he told me that is because it is of the highest cut quality, and showed me the beautiful pattern of hearts and arrows, as well as talked to me about the importance of ASET Scope and Ideal Scope images. One thing that he couldn’t explain was how to read ASET for princess cut diamonds. Is it different than for rounds? What do the different colors mean?”
The importance of ASET for princess cut diamonds:
ASET is the abbreviation for Angular Spectrum Evaluation Technology, which was developed by the American Gem Society Laboratory, as part of their Light Performance grading platform.
Due to a wide variance in the facet structure of princess cut diamonds, it is practically impossible to estimate the volume of light return and sparkle factor of a princess cut diamond by the numbers. And gemological laboratories such as the GIA only provide total depth and table diameter measurements, thus there is no way to determine the crown and pavilion measurements without additional computerized proportions analysis.
But even if you had all of the measurements of a princess cut diamond, it would be difficult if not impossible to accurately predict the visual performance by the numbers, because there is too much variation in the facet structure of the diamonds. One princess cut diamond might feature two chevron facets, another three, four or five chevron facets; and there is no consistency in the facet structure of the crown facets either.
ASET images of princess cut diamonds enable us to determine where in the room the diamond is gathering light from, and how evenly that light is being distributed and reflected back up towards the user. This insight is invaluable because it makes the difference between buying a princess cut diamond that is dull, flat and lifeless, or one which is bright, brilliant, and vivid, like those featured in the Brian Gavin Signature collection. Each one of which is cut specifically to exhibit the highest volume of light return and light performance.
What do the different colors of ASET represent?
The ASET scope uses the colors, red, green, and blue to represent light that is entering the diamond from different positions within a chamber that is designed to mimic the lighting environment of the earth’s hemisphere.
The color red represents light that strikes the surface of the diamond from perpendicular with the table facet, up to 45 degrees, which happens to be the brightest light in the room! Thus it is a good thing when the ASET image shows a lot of red, because that means that the diamond is picking up the brightest light available within the room, and reflecting it back up towards you.
The color green represents light which is the second brightest light source in the room, which is light that strikes the diamond from 45 degrees out to the edge of the horizon. It is important to understand that green represents light being reflected from the second brightest light source, it is still extremely bright, and is not considered a negative factor unless the majority of the light being reflected is green, it should be a trace element of sorts.
The color blue represents the contrast created by your head blocking light from entering the diamond, and the shadow of your head reflecting off of the pavilion main facets.
What to look for in a princess cut ASET image:
When shopping for a princess cut diamond, look for an ASET image that exhibits a lot of red, which represents the brightest light within the room being picked up and reflected back by the diamond. And it should have a good amount of green, which represents the second brightest light source within the room, and helps to provide contrast in the form of secondary brightness that helps our eyes distinguish one pattern of light return from another within the diamond.
The pattern of light return in the form of red, green and blue should be fairly uniform, if you look closely at the ASET image of a princess cut diamond provided at the top of this page, you’ll see that the red, green, and blue colors appear in a pattern that is visually pleasing.