Which is better for evaluating a diamond’s light performance?
Despite their similar looks, there are different benefits and drawbacks between the ASET and Idealscope. Obviously, both can be used to assess the light performance of diamonds but they do it in a slightly different manner.
In this article, you will find out what the differences between an ASET and Idealscope are and which one you should use when selecting a diamond. Let’s jump right in…
If you look at an Idealscope, you can see that it consists of a black lens and a red reflecting material. The 10x magnifying lens allows you to see how much light return the diamond displays; red indicates light return, black indicates contrast and white indicates light leakage.
Here’s a schematic diagram of how it works and how it is used to reveal areas of a diamond that reflect light or leak light.
Basically, all you need to do is to scope your diamond through the idealscope and then compare it to the reference chart below. It’s simple, efficient and relies on hard tangible data for analysis.
The ASET was developed by American Gem Society (AGS) as a means to evaluate a diamond’s interaction with light. By using color-coded images, it enables the viewer to see how well or badly the diamond handles light rays.
When you are looking at an ASET scope, you will see a blue, a red and a green belt. The colors represent contrast/head shadow, intense light return and indirect light return respectively. White/black areas represent areas of light leakage.
The 2 examples below show an ASET comparison of a well cut (left) round diamond against one that is poorly cut (right).
Here’s a schematic diagram of how the ASET scope works when it is used to analyze a diamond.
Don’t worry if all these still sound too technical to you. All you need to do is to get an ASET image of your diamond and compare it to the reference chart here to find out the light return capabilities of your diamond.
Both the idealscope and ASET tools reveal areas of light leakage indicated in white (or black if it is not backlit), but the ASET image contains more information for evaluating light performance.
Idealscope images are depicted on the left and ASET images on the right.
Thanks to the lower green belt, the ASET is also able to highlight the intensity of light that is being returned to the eye. The ASET tool also works well on both loose and mounted diamonds without a need for backlighting.
The other advantage of using the ASET tool is that it isn’t limited to round diamonds and works very well with fancy shaped diamonds too. However, it does require more knowledge to correctly interpret the different colors of an ASET and understand what they mean.
As for the idealscope, it’s a really basic tool that is very simple to use and understand. It’s useful for assessing optical symmetry and brightness for round diamonds. However, the downside is that it doesn’t work well with fancy shapes.
As you can see in the princess cut example above, the idealscope image shows a saturated red across the diamond and there is a lot of missing detail about how the facets handle light. In contrast, the ASET is able to paint a complete picture of light return for the fancy shape diamond.
The answer is “it depends”. If you are buying a round diamond, you can use either one to make a proper judgment of cut quality. If you are buying a fancy shape diamond, you should only rely on the ASET.
The ASET scope obviously provides more information with regards to the light performance of the diamond. However, it does take a little more knowledge to decipher what the individual colors mean and how they correlate to a diamond’s optics. In general, the ASET is the preferred tool for evaluating fancy cut diamonds.
However, the simplicity of the idealscope brings certain lucidity to the table. You do not really need any gemological qualification to figure out which type of Idealscope images to look out for. Red is desirable and indicates light return while diamonds with too many white areas indicate problems with light leakage.
Neither of the tools is black magic and both are highly useful.
If you are buying a diamond in a physical retail store and you want to see a little more than what a simple 10x jeweler’s loupe might tell you, an Idealscope is – pun intended – the ideal tool you should use. Either way, both scopes will offer you compelling information in a non-technical manner.
If you are buying diamonds online, you should always request Idealscope/ASET images on top of photographs or videos. This will enable you to scrutinize performance in more details.