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Wondering Why Your Diamond Sparkles?

We love diamonds for different reasons. Whether it’s because diamonds represent a symbol of love, or mark a joyous moment in time, there is one constant: we truly, madly, deeply love diamonds that sparkle.

Did you know there’s a tool that illustrates sparkle? We call this device the ASET®. On our grading reports, it’s represented as the Light Performance Map and the two terms are interchangeable.

Let’s go beneath the surface of the diamond to learn how sparkle occurs.

round brilliant diamond

Fact: Diamonds of even poor quality, given the right light, can sparkle.

The ASET® is a powerful device that can help you better understand how your diamond will likely appear in different light, whether it’s sunlight, office lighting, candlelight or any other kind of light.

The ASET® provides two critical pieces of information: Light Performance and Optical Symmetry.

We’ll explain more on these two terms in a moment. First, let’s cut right to the heart and soul of the ASET®, namely, this image:

aset image


This is a diamond viewed under the ASET®. The image kind of resembles a kaleidoscope, right? It’s a mosaic of four colors: red, green, blue, and gray. The image shown here represents a perfectly cut, AGS Ideal® diamond. Notice how you don’t see much gray? And what do the red, blue, and green mean? Let’s examine the different colors and learn how each one contributes to a diamond’s sparkle.

The ASET® is a symmetrical mosaic of red, green, blue, and gray. The four colors form a team, and each one plays a role in creating sparkle. This is a team, though, that thrives on one word: contrast. The dark areas in the diamond make the bright areas brighter.

RED in the ASET® image represents areas in the diamond that are typically bright and produce the most pronounced sparkles. The image shown earlier is predominately red. That’s emblematic of an AGS Ideal® cut diamond.



GREEN represents areas in the diamond that are less bright. The green areas are able to produce sparkle, but the sparkle doesn’t shine as brightly. A diamond needs green areas, because green adds to the brilliance (shine) of a diamond.



BLUE is the control-center of contrast. Blue is the balanced pattern of bright and dark areas in a diamond. If you look at your diamond under the most recent version of an ASET® and see a dark blue, We call that “ultra-high” sparkle. That’s the kind of sparkle that stands out from across a room.



GRAY represents areas that do not produce sparkle. Remember that AGS Ideal® image above? It didn’t have much gray. Here’s something important to remember: There’s only one AGS Ideal® and it refers to a diamond specifically graded by AGS Laboratories, meeting its precise standards for the AGS Ideal® cut. If a jeweler tells you a diamond is “Ideal,” clarify that it’s actually an AGS Ideal®. Otherwise, you won’t see the similar pattern of red, green, and blue as shown above.



As we move on from the colors, keep this in mind:

Sparkle + Brightness + Contrast = Overall Beauty

Earlier we said that the ASET® provides two important pieces of information that explain the sparkle in your diamond. The first of these two factors is Light Performance. Let’s break this word apart to really understand what is meant by Light Performance.

Light represents brightness, right? You turn on a lamp and you can see better. If the light is turned “on” in a diamond, you are going to see an interplay of light dancing from the diamond. The more you see, the better the diamond is performing.

From a more technical standpoint, Light Performance is the diamond’s brilliance, fire, and, yes—its sparkle.

Light Performance is the reason you like to look at a diamond.

Hold up your diamond and turn it gently from side-to-side. You see a dance of white and colored sparkles across the diamond.

Light Performance is exciting, dynamic and it grabs your attention. Light Performance is the rock star behind the sparkle.

If Light Performance is a rock star, then Optical Symmetry is a maestro. Just as a maestro would be focused on the execution and precision of a performance, so is Optical Symmetry.

Optical Symmetry is the diamond’s pattern—how symmetrical the diamond looks. The diamond’s symmetry is dependent on the quality of how well (precise) the diamond is cut—and a diamond’s cut is linked to the quality of its sparkle.

The overall distribution of the four colors as viewed under the ASET® represent the diamond’s symmetry. Simply put, diamonds cut to the highest level of symmetry will have the most symmetrical images when viewed under the ASET®.

There are three different types of ASET® images, and each one has its benefits. Which ASET® is your jeweler using to show you your diamond?

Here’s a quick snapshot of the attributes of all three, accompanied by an illustration of what a diamond will look like.

Primary ASET®

  • Provides information on the light return of a diamond, with a balanced mix of contrast.
  • The contrast in this image is a virtual representation of the possible contrast, which may vary depending on the light.


Optical Precision ASET®

  • Provides information on the light return of a diamond, with a balanced mix of contrast.
  • Provides info on the optical symmetry of the diamond, while simultaneously giving information the light performance.
  • Provides supplemental information on the unique patterning and optical symmetry of the diamond.

Advanced ASET®

  • Provides information on the light return of the diamond, with typical and exaggerated contrast.
  • New dynamic contrast provides supplemental information on the diamond’s brightness and sparkle.


Whichever ASET® your jeweler uses, it will help you understand how your diamond handles light, and the key ingredients of the brightness and fire that contribute to your diamond’s sparkle.

We mentioned this formula earlier. If you have one take-away from reading about the factors that go into a diamond’s sparkle, let it be this formula. If you want to learn more, fill out the form below, and AGS Laboratories® will send you information that digs deeper into why a diamond sparkles.

Enjoy your diamond and all the happiness—and sparkles—that it brings.