A Guide to Cloudy Diamonds

We normally think of fine diamonds as being perfectly transparent, brilliant, and sparkly. But sometimes we see diamonds that look cloudy, hazy or dull. Problems with the diamond’s transparency may be the culprit and can result from several different causes. A diamond that is not properly cut will leak light and appear less brilliant and fiery than it should. Strong fluorescence can also sometimes result in a diamond with a hazy or oily appearance. A diamond that has not been cleaned for a while can look milky due to a buildup of film and dirt on its facets. Cloudy diamonds can also have diminished transparency from inclusions or other characteristics intrinsic to the crystal from which they are cut.
Cloud Inclusion
Cloud Inclusion on the Certificate plot and photographed
The more pure a diamond is (the higher its clarity grade), the less that intrinsic characteristics will contribute to any cloudiness or haze that might be observed. Cloudy diamonds are rare in the upper clarity grades, but not uncommon in the lower clarity grades. Certain types of inclusions and graining can sometimes reduce transparency in a diamond to a noticeable degree. If transparency is degraded enough, the diamond can appear obviously cloudy or milky and lacking in luster. In other cases, the effect is subtle and may not be noticeable to any but the most trained eye.
Picture a nice clean mirror. Now picture one that has been handled and has fingerprints and smudges on it. You can still see your reflection but it is not as crisp and clear. Some of the light that should be returning a perfect reflection is being scattered or blocked resulting in slightly diminished image. Something similar happens when diamonds have inclusions of certain types and concentrations.
A faceted diamond is essentially a miniature sculpture made of tiny mirrors. Light is gathered through the crown of the diamond, bounces around from facet to facet internally, and then is returned back to the eye through the crown. A well cut diamond has the potential for that process to be efficient and accurate and to result in generous amounts of brilliance and fire. However, even in ideal or super ideal cut diamonds, inclusions or other characteristics can impede enough light rays to result in diminished optical performance.
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Do Diamond Clouds make a diamond look cloudy?

One inclusion type that sometimes create concern for diamond shoppers when reading a lab certificate are “clouds”. A cloud is the gemological term for a group of very small pinpoint inclusions. Clouds can take many forms, be of different sizes and densities, be black and easily visible under magnification, or be almost transparent. The mere fact that a cloud is listed on a diamond report does not mean the diamond will be cloudy, or that there will be any appreciable loss of transparency.
On the other hand, a cloud or group of clouds can be so extensive in a diamond that while individual inclusions making up the cloud are extremely difficult to see, even with magnification, the diamond can suffer from significant loss of transparency and performance. Diamonds such as these can appear obviously hazy. And in between the extremes there is a range of impacts, some of which can be so subtle that only an experienced professional can detect the effect.
For more information, please see our article on Diamond Cloud Inclusions.

Clouds, twinning wisps and graining

We have already mentioned cloud inclusions as being capable of impacting transparency if found in large enough areas and/or high density. These amorphous and diffuse inclusions by their nature can scatter light like smudges on a mirror, and result in lack of crispness. Similarly, twinning wisps and graining can interfere with the pristine propagation of light through a diamond. These inclusion types are the result of disruptions in the crystal growth that can cause interference with light rays passing through them, thereby affecting the fidelity of the propagation of light rays within the diamond. While these inclusion types can be very difficult or impossible to resolve with the naked eye, and can present some level of difficulty even for graders to see and locate, they can degrade transparency to the same degree as cloud inclusions. Again, it depends on how many and how concentrated and dense they are. In the upper clarity grades, they are almost never a cause for concern.

Transparency and color

We perceive color because the object reflecting the light back to our eye absorbs some of the wavelengths and reflects the rest. Depending on exactly which wavelengths are reflected we will perceive a particular color. If the object is perfectly clear it will reflect all the wavelengths and will look white or colorless. Therefore, any diamond that is not perfectly colorless is technically absorbing some of the light energy that enters it and not returning it to the eye. If we look at extremes like dark brown or black diamonds, they do not exhibit much in the way of brilliance. But in the colorless and near colorless range, the amount of energy absorbed is negligible, and light performance is not appreciably diminished by absorption.

Does Fluorescence make a diamond look cloudy?

About 30% of diamonds exhibit a property called fluorescence. They are energized by ultraviolet and visible violet wavelengths causing them to glow. This fluorescence is almost always blue and can vary in strength. The effect is normally only visible in a darkened room with a black light, which is how it is tested in the lab.
It is widely known that strongly fluorescent diamonds can sometimes look hazy or milky in light with high intensity UV light such as daylight. Fluorescence does not always cause this diminished transparency, but it is something to be aware of. It is important to remember that in order for fluorescence to be activated, the light source has to be very high in UV wavelengths. Most indoor lighting environments are incapable of causing diamonds to fluoresce to the level that any effects can be observed. Therefore, fluorescence alone does not usually make a diamond look cloudy in most lighting environments. And for the same reason, fluorescence rarely has a grade whitening effect as is often claimed.
For more on this interesting property please see our article on Diamond Fluorescence- Good of Bad?

Cloudy Diamonds in the Si and Imperfect grades

In the upper clarity grades of Flawless to VVS transparency issues are essentially non-existent. By definition these grades are so pure that it is extremely difficult for an experienced grader to locate any inclusions. In the VS grades in general transparency problems are unlikely, but possible. In the Si and Imperfect grades, certain information contained in the stone plot, keys to symbols, and Comments can indicate likely transparency issues.

How does a non-expert know if a diamond is suffering from diminished transparency?

Unfortunately, lab reports do not directly state whether a given diamond may be cloudy. However, a report is written in certain ways that provide an indication whether a transparency issue is unlikely, probable, or likely.
It is also sometimes possible to detect this issue by analyzing photos and videos posted online. More on this subject below. First, some guidance on gaining insight on potential transparency issues from the lab report itself.

How lab reports communicate potential transparency issues

We think of a lab report as a record of the diamond’s 4C’s – Cut, clarity, color, and carat. But the report communicates other important information about some of the more nuanced aspects of the diamond, including to an extent its transparency. In the stone plot, keys to symbols, and comments sections of the report you can often learn indirectly about potential transparency issues.
Cloud Key to Symbols
The stone plot on a grading report is meant to help positively identify the diamond and to support the clarity grade. It is important to understand that not everything going on in the diamond is always included on the stone plot. Especially in the lower clarity grades, there can sometimes be many inclusions and inclusion types. The Keys to Symbols list under the stone plot place the inclusion type in order of its impact on the clarity grade. Therefore, if a diamond of Si1 clarity has keys that list crystal, feather, and cloud in that order, the cloud inclusion has the least influence over the clarity grade.
The Comments field is another area of a grading report where information pertaining to potential transparency issue may be found. As mentioned, the stone plot will not necessarily show all the inclusions in the diamond. It is common for notes such as ‘additional clouds not shown’. This is a confirmation that not all inclusions in the diamond are presented in the plot. And if the clarity grade is in the Si or Imperfect range with clouds or twinning wisps as the grade setting inclusion type (listed first under Keys), then a comment of additional clouds, twinning wisps or graining is an indication of potential transparency issues.
Clouds In Comments
This form of reporting on transparency is not perfect. It’s a little like reading tea leaves. But a smart shopper aware of this form of communication can apply extra scrutiny when these flags are present. Where a diamond has many flags, it is highly recommended to have an independent expert evaluate the diamond with special attention to determining if the inclusions present diminish transparency or performance. The effects can be subtle and a trained eye is required to make an accurate assessment.

Clarity Grade Based on Clouds

One of the strongest signals that a diamond might have compromised transparency is the Comment in an Si or Imperfect clarity that says ‘clarity grade based on clouds not shown’. This is an indication that the cloud or clouds are so large that they would extend across all or most of the stone plot. This is also an indication that there likely is some degree of transparency impact, and needs to be carefully evaluated.
Clarity Based on Clouds not Shown
Not all Eye-clean diamonds are created equal.
Many shoppers look for eye clean Si or Imperfect diamonds, as many bargains may be among this category of diamond. But not all eye-clean diamonds are the same. Many cases where diamonds are technically eye-clean and seem like a bargain, transparency is a problem. And in many cases a seller looking to make a sale will be the last person to alert you to this issue. Understanding how to read a lab report, and dealing with ethical and knowledgeable vendors is the best way to ensure that you avoid potential problems and get everything out of the diamond that is important to you.

Transparency issues in VS clarities

We have seen that under certain circumstances diamonds in Si and Imperfect clarity grades can have compromised transparency resulting in loss of performance due to transparency deficits. And we have learned that this problem is essentially non-existent in the highest purity diamonds from Fl-VVS2. But what about those diamonds in the value sweet spot of VS1-VS2? Let’s focus on VS2. This grade represents a purity defined as having inclusions that are minor and require effort for an experienced grader to see at 10x. So a VS2 diamond is much less likely to have a transparency issue, even with a cloud or twinning wisp grade setting inclusion. However, clarity grades are small ranges along a continuum, so it is possible for that VS2 to be on the borderline of Si1, a grade category that we have pointed out can contain diamonds with subtle to significant transparency deficits. So it is still prudent to read the gemological report carefully and to otherwise verify that the diamond does not have any haziness.
Similarly, it would be highly unusual for a VS1 to have compromised transparency. However, it is not unheard of. It could possibly be on the borderline of VS2 and have a chance of exhibiting cloudiness, but it is highly unlikely. Careful vetting by a trusted seller, especially a seller of owned in-stock inventory will almost certainly eliminate this risk.

Spotting transparency issues in images and videos

It is sometimes possible to spot transparency issues in reviewing photos and videos posted online. However this is not foolproof and requires a frame of reference to compare against. That frame of reference is best provided by companies that image their inventory in an accurate and especially in a consistent way.
Clear Diamond
Clear Diamond Photographed in Controlled Environment
Cloudy Diamond
Cloudy Diamond Photographed in Controlled Environment
Sometimes a hazy stone can be spotted in a face up still photo. A 360 video is even more revealing. However, it very much depends on the light source used. Hard, directional lighting is more likely to illuminate the inclusions making the stone hazy. By comparing a stone suspected of having a transparency issue, with another stone of very high clarity that is imaged in exactly the same way, subtle transparency differences can often be detected.
Clear Diamond
Clear Diamond Photographed Under Direct LED Lighting
Cloudy Diamond
Cloudy Diamond Photographed Under Direct LED Lighting
Unfortunately, it is usually not possible to confidently compare different vendors offerings in this way as there is little standardization in photo setups and lighting in the industry. But within some vendors’ listings this method can provide useful analysis. Still the best assurance is to have the vendor’s gemologists to review the diamond personally for this specific concern.

Cleaning your Diamonds

Cloudiness in a diamond is not necessarily a permanent condition. Perfectly transparent diamonds, can start to look cloudy and lifeless over time. This may simply be a case of the diamonds having developed a film of dirt and grime. This film actually changes the optical properties of the mirrors that make up the facets of the diamond, allowing light rays to leak through them instead of being fully propagated internally and returned to the eye, and leaving them looking foggy and dull. Because this condition develops slowly, it is sometimes not even noticed. Until the piece is properly cleaned and you see it in all its original glory, you often don’t realize how dirty it has gotten. Keeping diamond jewelry clean is easy to do, and basic regular maintenance can keep film from building up to the point that it has to be professionally cleaned. It is recommended that every year or so you take your fine jewelry in for a professional cleaning to restore its full brilliance and luster. This also allows for proper inspection and discovery of any issues that might need attention, such as prong repair or stone tightening.
Diamond that Has Dirt on the Pavillion
Dirt build up on the pavilion of a Round Diamond
A diamond with compromised transparency will never be fully brilliant no matter how clean you get it and no matter how precisely it is cut. But a cloudy diamond that simply needs a good cleaning can easily be restored to full brilliance.
For more info please see our page on caring for your diamond jewelry.

Precision Cut diamonds and Transparency

Precision cutting of diamonds is practiced by a select number of diamond manufacturers operating from a philosophy of cutting for beauty over weight. The design and craftsmanship of the diamond, requiring more skill, more time, and often the loss of more weight from the original crystal, is all intended to optimize the diamond’s light performance -brilliance, fire and sparkle. That objective cannot be fully accomplished, even with the finest cutting, if the material itself is compromised in terms of transparency.
Many diamond shoppers are starting to take a great interest in diamond cut quality because they do in fact want the most beautiful diamond their money can buy. Some buyers who immerse in cut quality analysis, pouring over angles and percentages on reports and critically analyzing nuances of diagnostic imaging sometimes do so without a full appreciation for the limitations of those evaluations. It is not uncommon to see a shopper obsessing over a minor defect in a hearts and arrows pattern or a small spot of green on an ASET light map, while seemingly oblivious to the implications of the Si2 grade based on clouds not shown!
It is especially important that the shopper looking for optimal cut quality and light performance be cognizant of transparency issues and how to spot them.

Virtual diamonds vs in-stock diamonds

With regard to cloudy diamonds, diamonds with cutting faults, durability issues and other detriments, it is important to understand the nature of ‘virtual inventory’. This term refers to inventory listings that appear on multiple sites that are not owned or in the possession of the companies listing them. They are inventories offered up by various manufacturers to an international database after being offered to their cash buyers first.
All manufacturers have client who select diamonds in person and buy them outright inventory, or have production agreements for diamonds that meet their particular specifications and qualifications. To a significant extent, round diamonds on the virtual market are seconds. They have been passed over by the professional buyers who invest in diamonds for stock. Diamonds with transparency problems, even if in desirable size, color, clarity combinations, and even when cut with high precision, are passed up for one reason or another by professional buyers.
Yet, those diamonds still have to be sold. So they are put into lists that find themselves in a global database and on the websites of dozens of different retailers who have never actually seen them. They also have no way of physically evaluating them prior to sale.

Where to find the best diamonds

Well, we may be a little biased but we feel like Whiteflash is your very best source for diamonds and engagement rings. We specialize in precision cut ideal and super ideal diamonds of the ultimate light performance. We buy our diamonds and have them in-stock. They have been fully vetted by the AGS Laboratories or the GIA, and have passed additional testing, imaging, and strict vetting by the Whiteflash gemological review team. All of our in-stock diamonds are ready for shipment immediately upon receipt of payment, and they are available exclusively at Whiteflash. You will not see them on any other website or in any other store.
In addition to our in-stock inventory, we do offer access to virtual inventories. We offer this service primarily for clients that are looking for fancy shape diamonds or specific diamonds that we do not have in stock. The difference between Whiteflash and others when it comes to virtual diamonds is that we bring our full expertise in light performance to bear prior to delivery of the diamond. We provide careful vetting and advanced light performance images on every diamond we offer, so clients can be fully confident that they always know exactly what they are getting.
We have been providing brilliant experiences for clients all over the US as well as dozens of international locations since the year 2000. We are members of the American Gem Society, and have been a BBB Winner of Distinction every year since 2004, having won the prestigious Pinnacle Award multiple times. Thousands of 5 star online reviews tell the story of Whiteflash better than we can ourselves. We would be honored to be your diamond vendor!

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