I bet you have already noticed how much there is to learn once you start digging into the diamond world. You just want a beautiful diamond, so how did you end up reading about ASET now? It is a good thing though. You know for sure you are getting your money’s worth.
Now it is 2025 and the diamond world is changing fast. There are new technologies, more virtual shopping and all kinds of digital reports. Some people are starting to ask if ASET images are still as important as they used to be. The truth is: understanding how a diamond handles light (its real performance) is just as valuable as ever, whether you shop in person or online.
In the video below you’ll see three different ASET tools in action: first, the original handheld AGS ASET Scope. Then, a laboratory ASET imaging system used for analyzing multiple diamonds and finally, the modern metallic AGS ASET Scope preferred by professionals today.
If you are reading about ASET images, you are already ahead of most shoppers. You want to make sure your diamond is not just beautiful on paper but truly stands out in real life. I am here to break down what ASET actually tells you, why light performance is worth your attention in 2025, and how to use these images to spot a diamond that delivers real brilliance.
Let’s get started.
What is an ASET Image?
An ASET image is a special kind of picture that shows you how well a diamond handles light. The name stands for Angular Spectrum Evaluation Tool and this tool was originally developed by the American Gem Society. In 2023 AGS and its laboratory fully integrated into GIA, so all the research, technology, and expertise behind ASET now live within GIA’s operations. This means that when you see an ASET image or report, it is backed by the combined legacy and innovation of both AGS and GIA.
Above you can see the original ASET Scope: this colorful, classic model is still available to buy online and works very well for personal diamond evaluation. However, in the video at the beginning of this article, you could also spot the latest metallic “Pro” version. This modern professional ASET Scope is not available for sale to the public, but it’s the tool used by diamond labs and industry pros today.
What makes the ASET image so useful is that it goes beyond the standard diamond grading report. While the usual 4Cs give you a good starting point, ASET lets you see the real story of how a diamond will look in everyday light. AGS used ASET images as a big part of their cut grade, and now GIA offers the AGS Ideal Report as a digital supplement to their own grading reports. One place you will still see this in action is Whiteflash, which is famous for their super ideal cut diamonds. The main advantage over other tools like Idealscope is that ASET provides more detailed information, especially for fancy shapes where cut grades are not always available.
In short, an ASET image is a visual guide that helps you judge a diamond’s brilliance, fire and overall beauty by showing you how well it uses the light around it. Of all the diamond imaging tools ASET is the most comprehensive for everyday shoppers. It reveals not only where light is returned or lost, but also the balance and distribution of brilliance and fire across the diamond.
Idealscope is quick and easy for checking light leakage (especially in round cut diamonds) and Hearts & Arrows reveals top-tier optical symmetry. ASET however, stands out as the best all-around tool for judging real-life diamond performance. If you only use one tool when comparing diamonds, make it ASET. It goes beyond the basics and gives you the confidence to pick a diamond that truly stands out.
For a full comparison check out my detailed guide: ASET vs Ideal-Scope vs Hearts & Arrows Images Guide.
How Does ASET Work?
The ASET tool is all about showing you how a diamond interacts with light. When you see an ASET image you are really seeing a kind of map of light return and leakage. The tool itself is a simple device that uses colored filters to highlight the angles at which a diamond is taking in and reflecting light.
Here is what happens. A diamond is placed inside the ASET scope, which has red, green and blue filters positioned at specific angles around the stone. The colored bands on the outside of the original ASET scope are not just decorative, but they directly represent the angles from which light enters the diamond, like you can see in the image above.
When light passes through these filters and into the diamond, the resulting image shows which parts of the stone are using light from each direction. The final result is a color-coded picture that tells you a lot about the diamond’s true performance.
Each color in the ASET image means something different:
- Red areas show the light that comes from the most important 45° to 75° angle, meaning light that enters the diamond from directly above. This light is the most important because it produces the brightest sparkle and is most visible to the eye when viewing the diamond face-up. In short: more red means more brilliance.
- Green areas represent light coming from lower 0° to 45° angles. This light is not as strong as red, but it still adds to the overall look and helps with contrast.
- Blue areas indicate regions where light is being blocked, often by your own head or body when you look straight down at the diamond. In real life these areas appear dark and add the contrast needed for lively sparkle.
- White or black spots are where the diamond is leaking light. This is the light that escapes through the bottom of the stone, rather than being reflected back up to your eyes. Too much of this and the diamond can look dull.
When you look at an ASET image, imagine you are looking down at the diamond as you would in real life. The red should dominate, with balanced areas of green and just enough blue for contrast. You want to avoid large patches of white or black, which signal lost light.
The ASET image works best when the lighting and angles are controlled. In a perfect world, every diamond would be measured under identical conditions, but in reality there are small differences depending on your source. That is why you should always compare ASET images from the same retailer or lab, rather than jumping between sources. Each seller or lab may use slightly different background. Some use white and others use gray or black, which can influence how the leakage zones or edges appear.
You can see the effect of these differences in the ASET images below. All three ASET images look different. The ASET image on the left appears more orange, while the one in the center has a darker shade overall. And the one on the right is almost entirely bright red:
Even ambient light in the room or stray sunlight can change the look of an ASET image, especially if the setup isn’t fully enclosed. The specific type of ASET device, camera quality and even how precisely the diamond is positioned all play a part. Sometimes, subtle differences in exposure or white balance can make colors look a little warmer or cooler.
You’ll also notice that the rightmost diamond has very little green area compared to the others. While this might seem impressive at first glance, it can sometimes signal an unrealistic or overly idealized ASET image, especially if everything appears too perfect.
In my experience overly idealized ASET images like the one on the right usually happen when the image is captured in highly controlled or even artificial conditions, sometimes with extra lighting, digital enhancements or post-processing that removes any minor flaws. These practices can make a diamond look better on paper than it will in real life. That’s why I always recommend being skeptical of ASET images that look “too perfect” or show almost no green or leakage at all. Real diamonds, even top-quality stones, typically display a healthy mix of red, green and sometimes small blue or white areas.
Even among top high-performance diamond vendors, you’ll notice real differences in ASET image quality. For example, here you can see the Whiteflash ASET image on the left and the Brian Gavin ASET image on the right:
The Whiteflash ASET image stands out for its true black background, high color contrast and its crisp facet definition. This makes it much easier to spot light leakage and judge overall performance. The Brian Gavin image on the other hand uses a white background, which makes it harder to see the edges and any leakage zones and the colors appear less vivid. For the most trustworthy ASET images and consistent presentation, I recommend using those from Whiteflash. You can learn more about their standards in my Whiteflash review.
Whatever the case, always compare Whiteflash ASET images to other Whiteflash ASET images and not to those from different vendors. This ensures a fair, apples-to-apples comparison and helps you judge performance based on consistent standards. In 2025, neither James Allen nor Blue Nile provide ASET images, not even for their high-performing diamonds like James Allen True Hearts. So, if you want consistent, trustworthy ASET images to guide your decision, Whiteflash remains your best option.
Should the Center Dot Be Red or Green?
Have you ever wondered why some ASET images have a green dot in the center, while others show a red one? You’re not the only one, I get this question from diamond shoppers with some regularity. The good news is that it’s nothing to worry about.
The color of the center dot in an ASET image comes down to the diamond’s pavilion angle and where the light is entering. If the pavilion angle is below 40.768°, the center of your diamond’s ASET image will show up green, because it’s reflecting light from below the 45° mark. If the pavilion angle is above 40.768°, the center shows red, since the light is coming from above 45°.
This isn’t just some random observation, it’s actually been studied in detail by the scientists at the American Gem Society (AGS). In their ASET guides, they explain that the pavilion angle is what determines if the center will be green or red and even a small change (literally fractions of a degree!) will flip it from one color to the other.
There’s even a little “twilight zone” where a perfect pavilion angle can fall right on the line, giving you a center that’s a mix of red and green. You might remember that the “perfect” pavilion angle for a round brilliant is anywhere between 40.6° and 41.0°, and this red/green flip happens right in that zone. But in the end, for super ideal cut diamonds, either color is perfectly normal and doesn’t make the diamond better or worse.
So don’t stress about the center dot! As long as the rest of your diamond’s ASET image looks good (plenty of red, a healthy mix of green, minimal white or light leakage), you’re on the right track.
AGS Ideal Report ASET Image vs. Real ASET Image
This is a question I get a lot, especially from people shopping online: Is there a difference between a real ASET image and a computer-generated (CGI) one? The short answer is: yes, and it’s important to know what you’re looking at.
Real ASET images are actual photographs taken through an ASET scope with the physical diamond in hand. They capture all the tiny quirks and real-life light behavior of that exact stone: tiny asymmetries, small amounts of leakage or a little extra green or blue here or there. In other words: a real ASET image shows you the honest, “warts and all” story of the diamond’s light performance.
Computer-generated ASET images are rendered by software using a 3D scan or precise measurements of the diamond. These images are highly accurate in theory, but they almost always look too perfect: ultra-symmetrical, even colors and sometimes a suspicious lack of leakage or messiness. A computer model can’t fully account for tiny imperfections, polishing marks, or natural quirks in the diamond’s crystal structure, so these images show the diamond at its theoretical best.
Where will you see a digital ASET?
The only place most shoppers will ever see an official computer-generated ASET image is in the AGS Ideal Report by GIA (sometimes called the GIA-AGS Ideal Report). This premium report, available only for select high-performing diamonds, includes a digital ASET based on a 3D scan. You won’t find these digital ASETs in standard GIA or IGI reports, just in the AGS Ideal Report.
Why does this matter?
If you’re comparing two diamonds, always try to compare apples to apples. If one seller shows only computer-generated ASET images while another provides real scope photos, the differences you see may be just as much about the imaging method as the diamond itself. CG images are great for understanding a diamond’s potential, but real images give you the most trustworthy look at what you’ll actually receive.
Pro tip:
If you notice an ASET image that looks “too perfect”, ultra-crisp, zero leakage and with almost glowing colors, then there’s a good chance it’s computer-generated. Real photos almost always have a bit of natural messiness, even for the best-cut stones.
What about retailers like Whiteflash?
Whiteflash now sets the standard with their new Advanced ASET feature, providing three different real ASET images of every A CUT ABOVE® diamond. You get ASET images taken at both 30° and 40° angles, plus an additional hearts ASET view. These are ASET images for an 1.233 ct G VS2 A CUT ABOVE®diamond:
The angles refer to the “observation” angle or the tilt or perspective at which the ASET scope is positioned above the diamond when taking the image.
- The first 30° ASET image simulates how the diamond looks from a more tilted or side-on view, similar to how a diamond appears when you see it from an angle, like you often do when wearing it on your hand.
- The 40° ASET image is closer to a face-up, “looking straight down” view, the most traditional way diamonds are assessed. At this angle, you’ll notice more blue areas (dynamic contrast), which appear because your head or body naturally blocks some of the overhead light. This stronger contrast pattern is what creates those bold flashes of sparkle when the diamond moves.
- Hearts ASET view: This is a real ASET image captured from the pavilion (bottom) side of the diamond. It reveals the optical symmetry pattern known as hearts and provides a light performance map from the reverse perspective. Unlike a traditional hearts-and-arrows viewer, this is an actual ASET scope image, giving you extra insight into the diamond’s cut precision and optical symmetry.
By providing ASET images at both 30° and 40°, Whiteflash allows you to see how the diamond performs under both common viewing angles. This makes it easier to spot potential light leakage, weak areas or “dead zones” that might only be visible from certain angles. It’s much more informative than a single ASET shot from just one perspective.
But here’s a perfect example of why real ASET images matter. The three computer-generated ASET images above I just showed you were from a real AGS Ideal grading report from a VS2 Whiteflash diamond. And this is the same diamond in a real ASET image and an actual image of the same diamond:
Notice those dark spot in the ASET image? That’s the crystal inclusion blocking the light, something that digital ASET images almost never show. Digital ASETs are based on the diamond’s ideal proportions and symmetry, but they don’t account for real-world quirks like inclusions, polish marks or tiny natural imperfections. In this case, you can also see the same inclusion clearly in the diamond photo, which means this VS2 is probably not eye-clean or is at best borderline. Digital ASETs are based only on the diamond’s proportions and symmetry, not on real-world quirks like inclusions or polish marks. This is why I always recommend checking the real images and not just the report or a digital rendering.
One quick detail: this diamond’s pavilion angle is 40.9°, which is right in the “ideal” zone, but you might notice that the center of the real ASET image looks a little more green than the perfectly red digital version. That’s totally normal and just reflects how real diamonds interact with light, especially at this precise angle. It’s a good reminder that real ASET images always give you the most honest picture of a diamond’s light performance.
All in all, the combination of digital multi-angle ASET images from the AGS Ideal report and an additional real ASET photograph makes Whiteflash one of the most transparent and buyer-friendly vendors on the market.
Bottom line:
For the most reliable comparison, stick to real ASET photos whenever possible and always compare diamonds using images taken with the same equipment, under the same conditions and ideally by the same retailer or lab. When in doubt, ask the seller if the ASET is real or computer-generated. Reputable vendors will always tell you.
ASET for Fancy Shape Diamonds
If you’re shopping for an oval, cushion, princess, pear, emerald or any other fancy shape diamond, you’ll quickly realize that ASET images look a bit different compared to round cuts. Don’t worry, that’s completely normal!
Why fancy shapes are different:
Unlike round brilliants, fancy shapes don’t have standardized ideal proportions or symmetrical facet patterns. That means you’ll almost never see a fancy shape with a “perfect” ASET image full of uniform red and symmetrical patterns. In fact, it’s totally normal for fancy shapes to show more green or even some white (leakage) zones.
What should you look for?
- Red is still king: More red means more light return, which is what you want. But don’t expect as much red as you see in an ideal round diamond.
- Green and blue: Some green is normal, especially near the edges. Blue zones (contrast) can vary by shape and are not as critical as in rounds.
- White/leakage: A little is okay, especially at the tips or corners, but avoid stones where large areas are white or pale, those areas will look dull in real life.
Tips for using ASET with fancy shapes:
- Compare similar shapes and sizes from the same vendor or lab for the most useful side-by-side.
- Pay special attention to the center of the stone: excessive leakage here is a red flag.
- Use ASET together with high-quality photos and videos to get the full story.
Manage your expectations:
Even a gorgeous fancy shape will usually show less red and more green/white than a well-cut round. The key is to avoid major leakage and find a stone with good balance and sparkle.
Our Key Takeaway
ASET images are one of the best tools for judging how well a diamond handles light. If you’re buying online, make sure you’re looking at ASET images from the same source, taken under the same conditions, so you’re comparing apples to apples.
For shoppers who want top-tier performance, Whiteflash’s A CUT ABOVE® diamonds come with three digital ASET images (at multiple angles) on their Advanced AGS Ideal report. This is a huge plus for transparency and makes comparing diamonds much easier.
But here’s the golden rule: always try to check a real ASET image whenever possible. Digital images are great for understanding a diamond’s potential, but a real scope photo will show you exactly what to expect in real life: quirks, inclusions and all.
Stick to these tips and you’ll be in the best position to pick a diamond with true sparkle and performance.
FAQs About ASET Images
What's the difference between ASET and Idealscope? Which is better?
ASET gives you a more complete picture of how a diamond handles light by showing you red, green and blue areas (light from different angles and contrast). Idealscope mainly shows red for light return and white for leakage, which is great for spotting problems fast, especially in round diamonds. If you want the full story, ASET is more advanced. If you want quick and easy, Idealscope works too.
Can I take my own ASET image at home?
You can buy a handheld ASET scope and snap photos through it with your phone, but the results depend a lot on lighting and technique. Most jewelers use better setups and controlled light for reliable images. For casual checks or just for fun, a handheld scope works, but for serious grading stick to professional images.
What's the most important thing to avoid in an ASET image?
Large white or very pale areas, especially under the table (center), signal major light leakage. These zones mean the diamond is not bouncing back enough light, try to avoid stones with big white spots in the ASET.
Can ASET images be used for lab-grown diamonds?
Absolutely. ASET works the same way for both natural and lab-grown diamonds. It helps you judge cut quality and light performance no matter how the diamond was created.
Are computer-generated ASET images trustworthy?
They’re accurate for showing the diamond’s “potential” if the scan is high quality, but they don’t reveal quirks like minor asymmetry, real-life inclusions or small leakage that a real photo might. Use them as a guide, but don’t rely on them 100% for final decisions, real images are always better.