Diamond Inclusions

There are the rare flawless diamonds. And then there are all the other diamonds! The vast majority of diamonds have imperfections in the form of inclusions; material trapped within the diamond or disruptions in the carbon lattice that are the result of formation deep under the crust of the Earth over billions of years. They are referred to by many as flaws but to others as ‘beauty marks’.
Diamond Inclusions
Microscopic Inclusions in the Table of a Diamond
Diamond inclusions take many forms and result in various impacts; from those that can only be seen by a trained grader working in a lab under a microscope, to moderately included diamonds with flaws visible to the naked eye, to heavily included stones impacting brilliance and/or durability. Inclusions help us to separate natural from synthetic diamonds, and they act as “fingerprints” to help positively identify an individual diamond. In some cases, very unique inclusions can help us to pinpoint the geographic location of origin of a diamond.
In this article we will discuss the most common types of diamond inclusions and their impacts. We will also touch on laboratory clarity grading and how to read a laboratory report to fully understand the characteristics of a diamond under consideration.
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Clarity is Rarity

As the saying goes, “clarity is rarity”. Among the top 5 clarity grades there is no difference in performance or beauty, all other factors being equal. Yet, there are price differences (sometimes significant) between each one. Why are the higher clarities more expensive if nobody can tell the difference? Rarity. Diamonds with fewer inclusions are rarer in nature than those that with more inclusions. Therefore, these harder to find diamonds command a premium even though most observers cannot see a difference. For this reason the astute shopper looking for best value can easily trade down to the VS and even Si grades to find diamonds that are just as beautiful for much less money than the technically more pure grades.

What are diamond inclusions?

A flawless diamond is pure carbon arranged in a crystal lattice that is essentially free of any other minerals. As the name implies, an inclusion is anything that is “included” or trapped within a diamond. The range of impurities possible is quite large. Small diamonds and other gem crystals such as sapphire and garnet can be trapped within a larger diamond, as well as other minerals and elements. Disruptions or breaks within the carbon lattice such as feathers, twinning wisps and graining are also considered inclusions. Any of these features, if visible to a trained grader at 10x magnification, are considered inclusions.
Though not technically considered “inclusions”, features such as chips and naturals are important to understand. Because they are superficial and not internal to the diamond they are classified as ‘blemishes’.

The most common diamond inclusions

The most common inclusions that you are likely to see in a diamond are crystals, clouds, feathers, twinning wisps, pinpoints and graining. They are so common that many diamonds contain just about all of them! In and of themselves, either separately or in combination, there is nothing inherently bad about any of them. The extent to which they should be of concern is in how much they impact the beauty or durability of the diamond. The clarity grade assigned by the lab provides some clues. The diamond inclusion scale below is known as the clarity grading scale.
Clarity Scale
In the upper clarity grades, particularly in VS1 and above, the inclusions are so minor that it is difficult to see them even with magnification. In these grades, the type of inclusion is of little consequence. They have no appreciable impact on performance, beauty, or durability.
It is in the lower clarity grades that distinctions become important. Those in the middle – VS2 and Si1 – are very unlikely to have any negative effect, but they require a careful reading of the lab report and/or inspection by a trained expert in order to rule out important issues.
The following are magnified images of common inclusions with extra magnification highlighting the feature. Below each image is the stone plot from its grading report to illustrate how the inclusions are listed. The feature listed first under Keys to Symbols is considered the most impactful in terms of the clarity grade assigned; the grade setting inclusion.
Diamond Inclusions
Diamond Inclusions
Crystal inclusion under the table that is reflected in the crown facets
Diamond Inclusions
Diamond Inclusions
Cloud and Crystal inclusions
Diamond Inclusions
Diamond Inclusions
Large indented natural inclusion
Diamond Inclusions
Diamond Inclusions
Twinning wisps inclusions

Surface breaking inclusions

Diamond inclusions that break the surface include feathers, knots, naturals, cleavages, and chips. In the vast majority of cases, these inclusions do not present an inherent problem. The diamond has come up from miles below the surface of the Earth through violent volcanic eruptions, and then has stood up to the heat and pressure of the cutter’s wheel. For the most part, gem diamonds are incredibly durable and can easily stand up to normal wear and tear in jewelry.
That said, a surface breaking inclusion can, in certain cases, increase durability risks. Diamonds do occasionally break or crack, but it is unusual to happen during normal wear. The most common way a diamond is damaged is in the setting process as the jeweler must put pressure on the diamond to securely set it.
Diamond Inclusions
Small feather inclusion at the girdle

Diamonds with points require special attention

Well cut round brilliant diamonds are incredibly durable. Even diamonds with surface breaking inclusions in the Si range likely pose negligible durability concerns with a well cut round. However, diamonds with very thin girdles and diamonds with points are a different story.
Cutting a diamond to a thin edge or a point provides an opportunity for an inopportune impact to cause damage. Inclusions such as feathers, chips, or naturals at vulnerable locations can be cause for concern. A stone plot with a feather running across a point on a princess cut or a pear shape, should be carefully examined for elevated risk.
The biggest danger in such a diamond occurs during the setting process, as the jeweler must put pressure on that area in order to securely set the diamond. A shopper is wise to only buy such a diamond from a vendor who will also be taking responsibility for setting the diamond.
A round diamond also has a point, called the ‘culet’ at the bottom. And this point is subject to damage during handling as a loose stone. But no pressure is ever put on that point during setting, and when set, the culet is completely protected from wear and tear. So a feather near the culet is not a cause for a durability concern.

Inclusions vs Blemishes

Inclusions are defined as features internal to the diamond. They may also extend to the surface. Blemishes are confined to the surface of the diamond and are usually minor in nature. Inclusions are plotted on a grading report in red whereas blemishes are plotted in green.
Examples of blemishes are chips, scratches, nicks, abrasions, bruises, polishing marks and naturals. Unless unusually large in size or number, blemishes rarely have any impact of performance or beauty.

What is a Natural?

A natural is a surface feature caused when the cutter leaves a small part of the raw diamond crystal on the finished diamond in order to keep from having to remove material all around the perimeter to maintain symmetry. This is done to retain carat weight that would otherwise be lost in removing the natural completely. Typically they are small and confined to the girdle area, but can be rather large if the cutter was taking liberties.
A natural is usually considered a blemish, but if the natural is significantly indented it falls into the internal inclusion category, and is termed an “indented natural”.
Diamond Inclusions
Large indented natural inclusion

Concrete vs Transparent Inclusions

Some diamond inclusions, such as crystals, can be very concrete in nature. They have a well-defined shape and are commonly opaque. Other inclusions such as clouds, twinning wisps and graining are amorphous in nature and are often very transparent. As such, many shoppers prefer these type of inclusions to more concrete and easier to see types.
Diamond Inclusions
Diamond Inclusions
Cloud inclusion

Diamond Grading Reports

A report from a top tier diamond grading laboratory like GIA and AGSL will provide an abundance of information that will verify the diamond is natural, positively identify the diamond, and provide qualitative analysis in an attempt to communicate the appearance and performance of the diamond. However, diamond reports have limitations as well. Seeing the diamond, being able to view video and advanced diagnostic images of the diamond, and getting consultation from a trained expert are all important additions to the data contained on a lab report.
In addition to the carat weight, dimensions, and cut, color and clarity grades the Stone Plot and Keys to Symbols map the features that support the clarity grade and positively identify the diamond. It is important to know that not every feature is necessarily mapped- only enough to accomplish those two specific goals. (*A stone plot is not included in the less expensive ‘Dossier’ report from GIA)
AGS Certificate
click to enlarge
GIA Certificate
click to enlarge
The inclusions listed under the stone plot are listed in order of their impacts on the clarity grade. The first feature listed is said to be the grade setting inclusion. Features listed last are the least impactful.
The “Comments” section of a grading report should also be noted. There, important aspects of the diamond are mentioned that may not be covered elsewhere in the report. For instance if the diamond is inscribed, a detail of the inscription will be found there. Also, clarity features that may be pertinent to the appearance of the diamond may be noted there. For instance, features not included on the stone plot will be mentioned in the "Comments" section.
It is sometimes necessary to understand the stone plot combined with Comments to better understand the appearance of the diamond and any potential issues. *See ‘transparency issues’ below.

Eye-Clean Diamonds

When discussing diamond inclusions one of the most common baselines for many shoppers is the concept of “eye-clean”. This means different things to different people, but essentially it is a diamond with no inclusions visible to the naked eye. The general feeling is that a diamond can have inclusions (they are even preferred to keep the price down), but an inclusion that is obvious to the naked eye is a non-starter for many shoppers.
However, there is quite a bit of subjectivity in this issue. For instance, it may be technically possible to see an inclusion with some effort and/or maybe from only a certain angle. Is that a deal breaker or do you just want to make sure that the first thing you see when you look at the diamond is not an obvious flaw jumping out? People differ in the their tolerance for “eye-clean” so shoppers should have a good idea what is important to them, and should make sure there is accurate communication between them and their vendor to avoid any disappointments.
Diamond Inclusions
Eye clean crystal inclusion
The Whiteflash definition of Eye-Clean is “nothing visible to the naked eye, to a person with 20/20 vision, from the face up direction, at a viewing distance of approximately 10 inches in normal overhead lighting.
If you are very near sighted or care about visibility at closer distances or other viewing angles, you should communicate that to your vendor. This is especially true if you are buying online.

Light Performance and Clarity Characteristics

Transparency issues

One of the more subtle but important negative impacts of inclusions takes the form of diminished transparency. We tend to think of diamonds as being perfectly transparent, but in fact some diamonds have a slight fogginess to them that often goes unnoticed by the untrained eye. And only by comparing side by side with a diamond of full transparency can the issue be confirmed. But a diamond with a transparency problem will never have peak performance in terms of brilliance and fire, even if eye clean and perfectly cut. It is therefore important to understand what signs to look for to spot potential transparency issues.

Clarity grade based on clouds not shown

A laboratory report does not grade transparency directly (a shortcoming of the grading process). However, there are some things to look for on a lab report that can signal a problem of this nature. This typically occurs in Si and below grades, but can sometimes be an issue with a VS2 that is borderline. The report will state in the Comments section that the “clarity grade is based on clouds not shown”. This is the biggest red flag for transparency issues for diamonds that otherwise look good on paper. Many times the diamond is completely eye clean, and can even be difficult to resolve any inclusions under magnification by those with limited experience.
This is particularly true of those diamonds that have stone plots that are almost entirely or entirely free of markings. This indicates that the cloud or clouds are basically present throughout the stone. This will almost certainly cause the diamond to have a slightly hazy appearance as light is being scattered and not propagated through the stone and back to the eye without interference.
Diamond Inclusions
A somewhat lesser set of clues can be deciphered by looking at the stone plot and Keys to Symbols of the plot. The grade setting inclusion is listed first, so if it is of the type that can scatter light such as a cloud, twinning wisp, or graining there is a possibility of a transparency issue. This potential is elevated if in the comments section there is mention of other clouds, twinning wisps or graining not shown. Again, this issue is only a concern in the Si and below grades.
It is a good idea when purchasing a diamond with any of these indications on the lab report to have the diamond carefully inspected by an experienced and credentialed third party professional.
This advice is particularly relevant to any shopper looking for outstanding cut quality. Cut grading does not take this factor into account. A diamond can be perfectly cut and still suffer loss of performance from the inherent transparency deficits of the diamond crystal from which it was cut. Peace of mind comes with due diligence.

Reflectors

An interesting type of diamond inclusion that can be quite remarkable is known as a “reflector”. It is really not a specific type of inclusion, it just happens to be located in a place within the diamond that gets mirrored around the diamond making it look like multiple inclusions. This is often the case when looking at the diamond from the pavilion side.
A diamond might just have one small black crystal, but it appears to be peppered with crystals. When looking at advanced diamond images like a hearts image or pavilion side ASET, a reflector can make the diamond look very messy. But in reality, the diamond may face up splendidly and may even be completely eye clean.
Another type of reflector that is not actually an inclusion at all is the reflection of a laser inscription. Since the laser inscribes the girdle of the diamond and leaves black vaporized carbon in the tiny etching, sometimes the inscription can be reflected back to the eye, particularly at certain tilt angles. This is usually not an issue, but in certain cases, particularly in some fancy shape diamonds, it can be an unwelcome effect.
Diamond Inclusions
Diamond Inclusions
Reflection of a laser inscription in a radiant cut is easier to see in the Ideal Scope image above left.

Less common diamond inclusions

There are a number of inclusions that are less frequently seen in high quality diamonds such as cavities, knots, etched channels, and laser drill holes.
Cavities are just what the name implies: a hole or divot at the surface of a diamond that appears to have been “scooped out”. Cavities are often associated with knots which are crystals that come to the surface. In some cases they can be dislodged, leaving a cavity. Think of a knot in a piece of lumber and how that knot can be punched out, leaving a knot hole. With diamonds it is not so easy to dislodge a knot, especially if it is well imbedded in the diamond. It is unlikely that a knot will come out leaving a cavity during wear. This usually happens during the cutting process.
An etched channel is a linear cavity caused by chemical processes during formation. Like cavities, if they are small enough they are not a significant issue. However, they can sometimes increase durability risk depending on their size and location. They can also trap dirt, possibly making them more visible over time. A professional cleaning will remove the buildup, but cavities and etched channels can be difficult to clean at home.
Laser drilling is a treatment that results in a small threadlike tunnel in the diamond. A laser beam is aimed at a dark inclusion and a hole is drilled so that a strong acid can be introduced under pressure to dissolve the inclusion. This does not improve the clarity grade but can make some inclusions much less noticeable. *Whiteflash does not deal in treated diamonds, so you will not see laser drills mentioned on any of the lab reports associated with our in-house diamonds.

Interesting Crystal Inclusions

There are any number of other minerals and crystals that can be trapped inside a diamond during formation. Sapphires, rubies and garnets are not uncommon to see. Sometimes they are quite beautiful under magnification. And a really good specimen add collector value to folks enamored by such rarities.
Diamond Inclusions
A golden colored crystal inclusion. Perhaps a yellow garnet!
Diamond Inclusions
Another view from pavilion side showing multiple reflections
Diamond Inclusions
Enlarged image of a very interesting diamond inclusion!

Summary/Common Questions

As we have seen, the clarity grade is based largely upon the number and size of the inclusions in a diamond. But in the upper reaches of the clarity scale there is no practical difference in terms of beauty, despite an increasing price. Clarity is all about rarity, at least in the top four or five grades. Perhaps this is why the most popular clarity grades are VS2 and Si1 where diamonds are usually eye-clean with no deleterious effects on transparency or durability, and are priced more affordably. In a practical sense diamond inclusions are good things! See our page on Si1 diamonds to learn more about finding great value on your diamond journey.
Shoppers gravitating toward these ‘value’ grades ask some common questions in order to feel comfortable with their selections.

What are the worst inclusions in diamond?

Inclusions in and of themselves are not inherently bad. Almost all diamonds have some inclusions. It is mostly a matter of degree. Theoretically, surface breaking inclusions such as feathers, knots, and cavities cause some concern for durability in certain cases. But if they are small enough, such concerns are usually not warranted. Diamonds with a clarity grade of VS1 and above are almost always immune from durability or transparency issues. In most cases, diamonds graded Si1- VS2 are also free of durability concern with some exceptions. It is in the Si2 and below clarity grades that both durability and transparency issues must be evaluated carefully.
I Clarity Diamond
I2 clarity Inclusions seen in the table
I Clarity Hearts
I2 clarity Inclusions seen in the pavilion

Diamond inclusions to avoid?

As mentioned above, surface breaking inclusions and blemishes can pose durability concerns in certain cases. This is not to say that you have to avoid all feathers, cavities, chips or naturals. These features at the girdle of diamonds with very thin girdle height do indeed pose a risk. Actually, the risk is more from the very thin girdle than from the feather in most cases!
Surface breaking inclusions are particularly problematic if they are located at a point on diamonds with points such as princess cuts, marquises, or pears. The point is vulnerable to begin with, and any inclusion at the point increases that risk.
Inclusions that impact transparency should also be avoided. Again this is a matter of degree and should be assessed by a trained eye if there is an indication on the lab report suggesting the potential for diminished transparency. In particular, shoppers looking for top cut quality should pay attention to this issue where warranted. This concern is only applicable to the lower clarity grades. VS1 and above this issue does not apply. And in most cases VS2 and Si1 are also unlikely to have transparency problems.

Do clouds make a diamond look cloudy?

Not usually. Clouds are simply clusters of many pinpoint inclusions. They can be very concentrated and dense or they can be sparse and virtually transparent. They can be very small or they can permeate the entirety of the diamond. (*see clarity based on clouds not shown below)
Clear Diamond
Clear Diamond Photographed in Controlled Environment
Cloudy Diamond
Cloudy Diamond Photographed in Controlled Environment
Only when features like clouds or twinning wisps are very numerous, very big, or very dense can transparency be impacted to an appreciable degree. See our page on cloudy diamonds for more info on this potential problem.
Clear Diamond
Video of Clear Diamond Under Direct LED Lighting
Cloudy Diamond
Video of Cloudy Diamond Under Direct LED Lighting

Our Recommendations

The best value range in terms of clarity are carefully vetted diamonds in the grades VS1, VS2 and Si1. Customers looking for elite purity can remove any concerns about negative impacts of clarity factors by choosing IF, VVS1 and VVS2 grades. For these shoppers we suggest our A CUT ABOVE® Collection Series that feature colorless (DEF) diamonds that are microscopically clean ( IF , VVS1 and VVS2). Because of the extreme precision of their cut, these are the ultimate in diamond quality – very literally the “best of the best”.

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