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Eye-clean is an unscientific term but a very important criterion for most diamond shoppers. Most people understand that virtually all diamonds have some flaws (even Flawless diamonds if the magnification is high enough!), but they would rather not see them with the naked eye. And shoppers can save significant money by dropping several clarity grades and still get an eye-clean diamond. But where to draw the line? In this article we will be talking specifically about natural diamonds. Most of the lab grown diamonds on the market today are in the upper clarity grades and are almost all eye clean, although transparency remains an issue with some due to structural defects in the carbon lattice.
Natural diamonds have a wide range of possible inclusions. Among the most common are crystals, feathers, clouds, twinning wisps, and pinpoints (tiny crystals). Clarity grades are based mainly on the number and size of inclusions and how easy or difficult they are to see at 10x. The Si range and below have inclusions that are somewhat to very easy to see at 10x and may be visible to the unaided eye. VS and above are generally eye-clean, but there are exceptions which we will talk about below.
Hard to See Inclusion Types
Many shoppers prefer inclusion types such as Cloud and Twinning Wisp because they are hard to resolve with the naked eye. They are amorphous areas with very small features that can be hard to distinguish, even with magnification. They can often look prominent on a stone plot yet completely invisible to the naked eye. They serve to bring the clarity grade down, thereby saving money, while at the same time resulting in a completely eye-clean diamond. There is a limit to the benefit of this as we will discuss below. Since these inclusion types tend to scatter light, if they are too numerous or too dense they can cause an appreciable loss of overall transparency.
Cloud inclusion – difficult to impossible to resolve with the naked eye
Crystals – aka “Carbon Spots” get a Bad Rap!
A crystal is a type of inclusion that is reflective or dark in color and can be easy to see with the naked eye if large enough and especially if located under the table. A crystal, or even a few crystals in a diamond, while capable of being seen with the naked eye, can often hide among the on/off and black/white scintillation of a diamond in motion. This is especially true if the crystal is located in the crown. And crystals do not scatter light the way some other inclusion types do. So, while many people do not want to see these so-called “carbon spots” with the naked eye, they might just make for a more beautiful diamond, and the camouflage given to them by the blinking of the facets can make them invisible to casual observation.
Crystal inclusion - in this case located such that it reflects looking like two crystals
Eye-clean Definition
As mentioned, “eye-clean” is not a scientific term. Laboratory reports will not directly tell you whether a diamond is eye clean or not because there are two many variables; viewing distance, viewing angle, lighting, visual acuity of the observer, and even size and shape of the stone come into play. The type and size of inclusions and their locations will make a difference. That information can be gleaned to some extent from a laboratory report, so informed predictions can be made. If a diamond online is listed as eye-clean you need to understand what that merchant’s definition of eye-clean is and make sure it is in line with your expectations. Your visual acuity may be above average, especially if you are near-sighted and can focus at very close viewing distances. The best overall definition of eye-clean, and the one we use is:
No inclusions visible to the naked eye of a person with 20/20 vision when viewing the diamond in the face-up position at a distance of approximately 10 inches under normal overhead lighting.
Bear in mind that a diamond that is eye clean from the face up position may have a visible inclusion from the side. The shape and facet design of the diamond can also influence whether a stone is eye-clean or not. For example, emerald cut diamonds are famously unforgiving in that the large table and long step facets make seeing inclusions much easier than in brilliant styles. For this reason, most emerald cuts on the market tend to be in the higher clarity grades.
The size of the diamond also makes a difference as clarity grading is somewhat relativistic. That is, an inclusion of the size that would make a 3 ct diamond a VS2 would likely make a 1 ct diamond an Si1. Since the inclusion is the same in both stones, it is just as likely that the inclusion in the 3 ct is visible to the naked eye, even though the clarity grade is higher.
Not all Eye-Clean Diamonds are a Bargain
Some inclusions that may not be visible to the naked eye can sometimes be worse than inclusions that are visible. A diamond can have clarity features or defects in its crystal structure that reduce overall transparency. Inclusion types like twinning wisps, clouds and graining individually or in combination tend to prevent light from propagating fully through the diamond resulting in have negative impacts on transparency. A diamond with reduced transparency can look cloudy or hazy. In many cases the effect is very subtle; the diamond just doesn’t have as much “life” as it should. It is not uncommon for a diamond with an eye visible inclusion to be much more beautiful than a diamond that is eye clean but has light scattering inclusions or defects that reduce brilliancy and fire.
This is NOT to say that any diamond with a cloud, a twinning wisp, or graining has an appreciable transparency issue. Learning to read a laboratory report and pick up on the nuances of their indirect communication is very helpful. The Comments section is often used to give the consumer a heads-up on a transparency problem. For example, in the Si range a comment of “clarity grade based on clouds not shown” is an indication that the stone may have a transparency issue. Stones like this are often a little hazy or “sleepy” and lacking in brilliance. A stone with this problem will never have optimal light performance even with a precision cut.
Tolerance for Eye-visible Inclusions
Just because an inclusion may be technically visible to the naked eye does not make it an undesirable diamond. In fact, diamonds that are fully transparent and precision cut are often far more beautiful than other diamonds, even if they are not completely eye clean. In assessing eye-clean we are looking for inclusions and focusing solely on them. But a casual observer sees the diamond in a more holistic way, focusing on the brilliance and scintillation and other beauty factors such as shape and style of the setting. A small crystal that could be visible if you were trying to see it, is very often lost among the blinking facets of a brilliant diamond.
Conclusion
Eye clean is a term that means different things to different people. Make sure you understand the merchant’s definition of eye-clean and ensure that it matches your own. And understand not only your own visual acuity and ability to resolve inclusions, but your tolerance for being able to see an inclusion with the naked eye. It may not detract at all from the overall beauty of the diamond. In a real way, tolerance of a visible inclusion is just like tolerance of a little body color. Not everyone feels the need for a technically colorless diamond. But many do.
What is your tolerance for eye-visible inclusions? Is it a deal breaker if an inclusion can be seen with the naked eye?
Natural diamonds have a wide range of possible inclusions. Among the most common are crystals, feathers, clouds, twinning wisps, and pinpoints (tiny crystals). Clarity grades are based mainly on the number and size of inclusions and how easy or difficult they are to see at 10x. The Si range and below have inclusions that are somewhat to very easy to see at 10x and may be visible to the unaided eye. VS and above are generally eye-clean, but there are exceptions which we will talk about below.
Hard to See Inclusion Types
Many shoppers prefer inclusion types such as Cloud and Twinning Wisp because they are hard to resolve with the naked eye. They are amorphous areas with very small features that can be hard to distinguish, even with magnification. They can often look prominent on a stone plot yet completely invisible to the naked eye. They serve to bring the clarity grade down, thereby saving money, while at the same time resulting in a completely eye-clean diamond. There is a limit to the benefit of this as we will discuss below. Since these inclusion types tend to scatter light, if they are too numerous or too dense they can cause an appreciable loss of overall transparency.
Cloud inclusion – difficult to impossible to resolve with the naked eye
Crystals – aka “Carbon Spots” get a Bad Rap!
A crystal is a type of inclusion that is reflective or dark in color and can be easy to see with the naked eye if large enough and especially if located under the table. A crystal, or even a few crystals in a diamond, while capable of being seen with the naked eye, can often hide among the on/off and black/white scintillation of a diamond in motion. This is especially true if the crystal is located in the crown. And crystals do not scatter light the way some other inclusion types do. So, while many people do not want to see these so-called “carbon spots” with the naked eye, they might just make for a more beautiful diamond, and the camouflage given to them by the blinking of the facets can make them invisible to casual observation.
Crystal inclusion - in this case located such that it reflects looking like two crystals
Eye-clean Definition
As mentioned, “eye-clean” is not a scientific term. Laboratory reports will not directly tell you whether a diamond is eye clean or not because there are two many variables; viewing distance, viewing angle, lighting, visual acuity of the observer, and even size and shape of the stone come into play. The type and size of inclusions and their locations will make a difference. That information can be gleaned to some extent from a laboratory report, so informed predictions can be made. If a diamond online is listed as eye-clean you need to understand what that merchant’s definition of eye-clean is and make sure it is in line with your expectations. Your visual acuity may be above average, especially if you are near-sighted and can focus at very close viewing distances. The best overall definition of eye-clean, and the one we use is:
No inclusions visible to the naked eye of a person with 20/20 vision when viewing the diamond in the face-up position at a distance of approximately 10 inches under normal overhead lighting.
Bear in mind that a diamond that is eye clean from the face up position may have a visible inclusion from the side. The shape and facet design of the diamond can also influence whether a stone is eye-clean or not. For example, emerald cut diamonds are famously unforgiving in that the large table and long step facets make seeing inclusions much easier than in brilliant styles. For this reason, most emerald cuts on the market tend to be in the higher clarity grades.
The size of the diamond also makes a difference as clarity grading is somewhat relativistic. That is, an inclusion of the size that would make a 3 ct diamond a VS2 would likely make a 1 ct diamond an Si1. Since the inclusion is the same in both stones, it is just as likely that the inclusion in the 3 ct is visible to the naked eye, even though the clarity grade is higher.
Not all Eye-Clean Diamonds are a Bargain
Some inclusions that may not be visible to the naked eye can sometimes be worse than inclusions that are visible. A diamond can have clarity features or defects in its crystal structure that reduce overall transparency. Inclusion types like twinning wisps, clouds and graining individually or in combination tend to prevent light from propagating fully through the diamond resulting in have negative impacts on transparency. A diamond with reduced transparency can look cloudy or hazy. In many cases the effect is very subtle; the diamond just doesn’t have as much “life” as it should. It is not uncommon for a diamond with an eye visible inclusion to be much more beautiful than a diamond that is eye clean but has light scattering inclusions or defects that reduce brilliancy and fire.
This is NOT to say that any diamond with a cloud, a twinning wisp, or graining has an appreciable transparency issue. Learning to read a laboratory report and pick up on the nuances of their indirect communication is very helpful. The Comments section is often used to give the consumer a heads-up on a transparency problem. For example, in the Si range a comment of “clarity grade based on clouds not shown” is an indication that the stone may have a transparency issue. Stones like this are often a little hazy or “sleepy” and lacking in brilliance. A stone with this problem will never have optimal light performance even with a precision cut.
Tolerance for Eye-visible Inclusions
Just because an inclusion may be technically visible to the naked eye does not make it an undesirable diamond. In fact, diamonds that are fully transparent and precision cut are often far more beautiful than other diamonds, even if they are not completely eye clean. In assessing eye-clean we are looking for inclusions and focusing solely on them. But a casual observer sees the diamond in a more holistic way, focusing on the brilliance and scintillation and other beauty factors such as shape and style of the setting. A small crystal that could be visible if you were trying to see it, is very often lost among the blinking facets of a brilliant diamond.
Conclusion
Eye clean is a term that means different things to different people. Make sure you understand the merchant’s definition of eye-clean and ensure that it matches your own. And understand not only your own visual acuity and ability to resolve inclusions, but your tolerance for being able to see an inclusion with the naked eye. It may not detract at all from the overall beauty of the diamond. In a real way, tolerance of a visible inclusion is just like tolerance of a little body color. Not everyone feels the need for a technically colorless diamond. But many do.
What is your tolerance for eye-visible inclusions? Is it a deal breaker if an inclusion can be seen with the naked eye?
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