ASET is a reflector tool and an important part of the AGSL light performance grading system introduced in 2005. It is used to analyze how effectively a diamond handles and reflects light, combining physical viewing with advanced ray tracing technology.

The concept is simple: when a diamond is viewed through the ASET tool, different colors represent light coming from various angles, while darker areas highlight light leakage. This makes it easier to understand a diamond’s brilliance, fire, and overall visual performance.

At grown-diamondss, ASET analysis is used to ensure every diamond meets high standards of light performance and quality, helping customers choose stones with superior sparkle and beauty.

In ASET, angular ranges are color-coded as green (0–45°), red (45–75°), and blue (75–90°). Most strong light comes from higher angles (red), while lower-angle light (green) is softer and reflected from surroundings. Blue represents light blocked by the viewer’s head, creating contrast that enhances sparkle and scintillation.

Well-cut round diamonds typically show mostly red, some green, a balanced blue pattern, and minimal light leakage. At grown-diamondss, this ensures diamonds with excellent brilliance and performance.

ne of the key strengths of ASET analysis is that it can be applied to diamonds of any shape, with grading systems developed for each. AGSL has created grading standards for shapes such as Round, Princess, Oval, Emerald, and select Cushion and proprietary cuts.

Fancy shape diamonds tend to have more variation in their ASET patterns. Even without an official lab grade, viewing an ASET image provides valuable insight into how effectively a diamond handles light.

There are different versions of the ASET tool, including handheld and desktop models, along with various photography setups. Some use a backlit background where light leakage appears white, while others use a dark background where leakage appears black.

In desktop models, the color-coded hemisphere is inverted and the diamond is placed upside down to keep the table perfectly flat. A black cover creates the dark background, and mirrors inside the device reflect the image to the viewer.

At grown-diamondss, these tools are used to accurately assess diamond light performance and quality

The handheld ASET model requires a bit more practice to use, but it is a simple, affordable, and highly portable option for diamond inspection. It can be used with or without a portable light source, allowing the diamond to be viewed in an upright position. When backlit, any light leakage appears as white, making it easier to evaluate performance.

Below are examples of an ASET for a top quality super ideal contrasted with an ASET of a diamond with compromised light performance.

The ASET framework is a core part of the AGS light performance grading system and is fully integrated into its software. The grading process uses advanced ray tracing on an accurate 3D model of the diamond to evaluate each facet’s contribution to brightness, fire, contrast, and light leakage.

It can also generate detailed ASET images and light maps. AGSL reports include these ASET light performance maps, with Platinum reports offering single or dual light maps showing both table and pavilion views.

Dual light maps are typically used for high-precision diamonds to demonstrate hearts and arrows patterning along with overall face-up light performance.

AGS has produced charts using composites of ASET images that illustrate how the ASET signatures change with different proportion sets.

Proportion sets along the “cutter’s line” that are known to produce top performance show ASET patterns consistent with expected levels of red, green, and blue. This provides visual validation of ASET theory.

ASET theory is a simple yet powerful method for evaluating diamond light performance. It serves both as a mathematical model used in advanced ray tracing and cut grading systems, and as a practical tool for real-world inspection. It can be applied to any diamond shape to better understand how the stone handles light.

In round diamonds, the center of the ASET map may appear green or red, representing the table reflection. This variation is generally not significant in assessing overall performance.

Another related tool is the Ideal Scope reflector, which works on a similar principle: red indicates returned light, black shows obscuration, and white represents light leakage.

At grown-diamondss, these tools are used to ensure accurate evaluation of brilliance and overall diamond quality.

The Ideal Scope provides a useful indication of light return and can also show some symmetry characteristics. However, compared to ASET, it offers less detailed insight into the quality, direction, and distribution of light returned by a diamond.

At grown-diamondss, ASET analysis is preferred for a more complete and precise understanding of diamond light performance and optical quality.