Cloud inclusions are tiny clusters of microscopic crystals trapped inside a diamond. They’re called clouds because, when grouped together, they create a soft, hazy area that resembles a wispy cloud under magnification. You won’t see each crystal on its own, but I’ve seen firsthand how they can either be completely harmless or absolutely ruin a diamond’s sparkle. And the difference between the two is easy to spot if you know what to look for.
Most people treat the word “cloud” on a grading report like a red flag. That’s a mistake. Some cloud inclusions are harmless and can help you save a lot of money if they don’t affect the diamond’s sparkle. But others sit under the table or spread like fog across the stone turning it dull and hazy even when the clarity grade looks decent. Knowing the difference is what makes or breaks the deal.
I am going to walk you through every type of cloud inclusion, what they look like, how they behave and when to run for the hills. We’ll look at real GIA clarity plots, zoomed-in images and side-by-side comparisons so you’ll know what’s safe, what’s risky and what’s downright ugly. By the end you’ll be able to spot a good cloud from a bad one in seconds and maybe even find yourself a hidden gem most shoppers would overlook.
Are Cloud Inclusions Bad in a Diamond?
Cloud inclusions can be good or bad. It all depends on where they are, how dense they are and how they affect affect a diamond’s sparkle. Some are completely invisible to the naked eye and save you serious money. Others sit under the table like a patch of fog and kill brilliance even in diamonds that look perfect on paper. The challenge is knowing which is which.
Let’s break it down.
Good Cloud Inclusions
These are the clouds you want to find. They’re small scattered and not dense enough to affect how light travels through the diamond. You usually find them in VS2 or SI1 diamonds, they’re sometimes the only reason the clarity grade isn’t higher and they give you a chance to grab a clean-looking diamond for less.
Signs of a safe cloud inclusion:
- Located off-center, not under the table
- Labeled as additional clouds not shown on the grading report
- No visible haziness in the video or image
- Sparkle and light return look strong from all angles
I get asked a lot about that one phrase on grading reports: “Additional clouds not shown.” Most of the time, it’s nothing to worry about. If a cloud inclusion is actually visible, it usually makes the diamond look milky or hazy in the photo or video. So in most cases, it’s pretty straightforward: if the diamond still looks crisp and sparkly, that cloud is either too faint or too scattered to be a real issue.
What you really want to watch out for are large patches that look milky or hazy-especially under the table. However, when browsing on sites like James Allen or Blue Nile using their 40x magnified videos, you might also come across diamonds that show small localized areas of cloudiness. These aren’t always bad, sometimes they’re just faint clusters that slightly soften a part of the image but don’t impact the diamond in real life.
I’ve personally reviewed hundreds of diamonds with cloud inclusions and here’s one example that shows what a harmless cloud looks like under magnification:
Notice the faint bluish patch at 9 o’clock, just left of center in the SI2 diamond shown above. This is a light-diffusing cloud inclusion. It’s subtle enough to avoid a milky or gray appearance, yet it’s visible under ideal lighting and strong magnification. Interestingly, this light-interrupting texture only becomes optically pronounced over the diamond’s bluish zones, a phenomenon not observed over the whiter regions of the diamond. This effect is tied to the cloud’s diffuse presence and how it interacts with light. In real-life viewing, this cloud inclusion is invisible and great example for a good cloud.
This SI2 diamond features the note “Additional clouds are not shown” on the grading report, a phrase that can cause concern for some shoppers. However, it’s not an automatic red flag at all. As always, you should inspect each diamond individually, but in many cases, this simply means there are additional minor clouds not plotted because they’re too insignificant to affect appearance.
The same note appears on this eye-clean I1 diamond which, despite its lower clarity grade, is also eye-clean and shares similar cloud characteristics as the SI2 example above. In my diamond clarity guide, I explain why I generally don’t recommend I1 diamonds, even if they appear clean. Eye-clean I1s are extremely rare and even then, there’s often little to no meaningful price jump between I1 and SI2 diamonds, making the risk just not worth it.
What these examples do show however, is that diffuse cloud inclusions are among the least problematic inclusion types. They’re often invisible to the naked eye, making them a fantastic opportunity to save money in the SI1 or SI2 range without sacrificing beauty.
PRO TIP:
Light-diffusing cloud inclusions, especially those only visible under strong magnification, are often your ticket to serious savings. They don’t impact structure and usually disappear completely in real-life viewing. James Allen has the largest online diamond inventory and the most advanced video tech, letting you examine each diamond in 360° HD to spot harmless inclusions that can save you thousands.
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Bad Cloud Inclusions
This is where things go wrong. The most notorious issue is the milky-looking diamond, the kind that appears dull or foggy. This happens when a dense cloud sits right under the table, acting like a haze filter. It softens the sparkle, dulls the brightness and kills the crisp light return you’d expect from a well-cut stone.
Some diamonds suffer from full-body haze, where the cloudiness isn’t isolated but instead veils the entire stone from all angles. The diamond on the left is such an example: it looks lifeless and hazy compared to the diamond beside it.
In some cases, the grading report lists only a single plotted inclusion: “cloud.” That alone isn’t always a problem but if the comment section says things like “Cloud not shown” or “Clarity grade based on cloud not shown,” that’s a serious red flag. It usually means the cloud is too large or dense to be plotted like a crystal or feather. These diamonds often fall into the VS2 or SI1 range on paper but completely fail the eye test: the cloud veils the entire face of the diamond and robs it of fire.
Red flags to avoid:
- Cloud located directly under the table
- Cloud is the only inclusion listed
- Video shows a hazy or milky look
- Sparkle seems weak or soft compared to other diamonds with similar specs
So cloud inclusions are not automatically bad. But if they interfere with brilliance or create haziness it’s an instant dealbreaker. Remember, you’re not buying a clarity grade. You’re buying how the diamond looks in real life. That’s why it’s critical to view the diamond yourself or work with a retailer that shows magnified images and videos.
Another thing to keep in mind to is the shape of the diamond. Step-cut shapes like emerald and asscher cuts tend to reveal cloudiness and other inclusions more easily than round brilliants because their broad, open facets reflect light differently and make internal texture more visible. These cuts produce less sparkle overall, so there’s less visual distraction to hide clarity flaws. In simple terms: less bling means more transparency, what’s inside the diamond becomes easier to see.
Cloud Inclusion Comments on GIA Reports: What They Really Mean
Diamond grading reports list additional observations in the Comments section and this is exactly where hidden red flags often appear. Just because a diamond looks clean in the plot doesn’t mean it performs well in real life. In fact, some of the most problematic diamonds have clouds that aren’t plotted at all, but still affect clarity and light performance.
This is especially common with milky or hazy diamonds, where clouds are too dispersed or subtle to map out like a feather or crystal. Instead, labs like GIA or IGI add short comments to warn buyers. These brief phrases can carry major weight and understanding them can save you from buying a dull or lifeless stone. Below is a reference list of common cloud-related comments you may encounter and what each one really means:
| Comment on Report | What It Means |
|---|---|
| “Cloud” (in the plot diagram) |
Meaning: A single inclusion type (cloud) is plotted directly on the clarity diagram, usually with no other inclusions present. Implication: Often indicates a large or diffuse cloud that spans a broad area. These can severely affect brilliance if dense or spread under the table. 🚩 Red Flag: Proceed with caution, especially in VS2-SI1 diamonds. Check for milkiness or dullness in video. |
| “Clarity grade is based on clouds that are not shown” |
Meaning: Clouds are the primary reason for the clarity grade but they’re too spread out or faint to be plotted. Implication: These can sometimes cause haziness, especially in SI2-I1 diamonds and occasionally in SI1 or even VS2. 🚩 Red Flag: Yes, if you’re in SI2 or lower but I’ve seen some SI1 diamonds with this comment that looked dull in person. Always check video and vendor notes for haziness. |
| “Clarity grade is based on internal graining” |
Meaning: The internal crystal structure of the diamond affects the clarity grade (often from strain or distorted growth). Implication: Can reduce transparency or brilliance slightly, especially if the graining is strong. 🚩 Red Flag: Especially in SI diamonds or fancy shapes. Look closely at sparkle in the video. |
| “Cloud(s) not shown” |
Meaning: Cloud inclusions are present but were not significant enough (or too diffuse) to be mapped on the clarity diagram. Implication: May be totally harmless but some unshown clouds can subtly impact sparkle. 🟡 Yellow Flag: Use imagery + vendor descriptions to confirm that brilliance is unaffected. |
| “Additional clouds are not shown” |
Meaning: Some clouds are already plotted but there are more faint or spread-out clouds that weren’t mapped visually. Implication: Can be harmless in higher-clarity diamonds but in SI1 or lower they sometimes contribute to dullness or a soft look. 🟡 Yellow Flag: Always double-check videos and vendor imagery in SI1 or lower to confirm the diamond sparkles clearly. |
| “Surface graining is not shown” |
Meaning: Graining (growth lines from crystal formation) appears on the surface, but not visible enough to be plotted. Implication: Often invisible but in some diamonds graining can cause subtle haziness, internal light distortion or even a soft milkiness. 🟡 Yellow Flag: Not a deal-breaker but worth double-checking via video or magnification. |
| “Internal graining is not shown” |
Meaning: Faint graining lines exist inside the diamond but are too fine or diffuse to map. Implication: Often harmless but in rare cases may affect transparency. 🟡 Yellow Flag: Safe if diamond looks bright. Just double-check performance. |
| “Pinpoints and clouds are not shown” |
Meaning: Extremely tiny inclusions (pinpoints) and minor clouds are present but not shown visually. Implication: Common in SI1 and VS2. Usually not a problem unless mentioned as the basis of the grade. 🟢 Green Flag: Not a big concern unless visual dullness is evident. |
The two most common comments I keep seeing regularly on grading reports when clouds are involved are:
First: “Clarity grade is based on clouds that are not shown.” As mentioned above, this is a red flag. It means the cloud is the main reason for the clarity grade, but it was too spread out or faint to be plotted. That might sound minor but in many (but not all) cases it actually does translate to a hazy or dull-looking diamond. Be extra careful if you encounter that comment.
Second: “Cloud(s) not shown.” This one pops up often and usually isn’t a problem, especially if you’re in the VS or SI1 range. It just means there are clouds present but they weren’t big or concentrated enough to mark on the diagram. Still, it’s worth confirming that the diamond looks bright and clean in the video. While most of these diamonds look great, the rare exceptions can have clouds that slightly affect light return or transparency, so a quick visual check is always smart.
Cloud Inclusions in Lab-Grown Diamonds
Cloud inclusions are still relatively common in lab-grown diamonds, especially CVD, but thanks to improved growth techniques since 2019, they rarely cause visible issues like haziness or dullness in modern stones.
In fact, some of the most affordable CVD lab-grown diamonds graded as VS2 or SI1 still owe their clarity grade to subtle but widespread clouds. These clouds are typically too faint or diffuse to be plotted and are instead referenced in the IGI comments section with phrases like “Clarity grade is based on clouds that are not shown.” When I see this comment on modern lab diamonds, I don’t panic because most of the time it doesn’t indicate a visual problem at all.
While that same phrase would often be a red flag in natural diamonds, suggesting a hazy or dull appearance, in lab-grown diamonds it rarely causes any visible problem. Despite how common cloud inclusions are in lab diamonds, I’ve found that they almost never result in actual haziness or a milky appearance. Nowadays, you can browse through hundreds of SI1 lab diamonds and you will most likely not even find a single milky or hazy diamond.
This difference comes down to how clouds form. In natural diamonds, clouds often develop under immense geological pressure and can spread unevenly or mix with other inclusions. In CVD lab diamonds, clouds usually form from structural irregularities during the growth process and are more evenly dispersed and less dense. That makes them much less likely to interfere with brilliance, even when they are widespread.
As I previously mentioned, the issue of haziness used to be more common in early CVD lab diamonds, especially before 2019 when growth techniques and post-treatment processes were less refined. That’s when you’d occasionally run into what I described earlier as bad clouds: dense or pervasive cloud inclusions that caused visible dullness or a milky appearance. But as of 2025, those kinds of clouds are virtually non-existent in modern CVD lab-grown diamonds. Most current inventory is much cleaner, especially from reputable vendors who no longer sell diamonds from that older generation. You’re most likely to encounter those older, hazy CVD diamonds through second-hand sellers, eBay, Facebook Marketplace or lower-end platforms that don’t vet their inventory or provide high-quality videos.
That’s why I now treat any cloud comment in lab-grown reports more as a yellow to green flag. As long as the video shows strong sparkle and light return, the diamond is usually safe to buy. For more details on evaluating eye-cleanliness, check out my full lab-grown diamond clarity article.
For buyers this means you should never rely on the clarity grade or the plot diagram alone. Always check the Comments section of the grading report and verify the diamond’s performance in video. But if the video looks great even with a cloud comment, chances are the diamond is just fine.
Our Key Takeaway
Cloud inclusions are one of the trickiest clarity issues to evaluate, mainly because they can either be harmless or completely ruin a diamond’s sparkle. In natural diamonds, clouds often appear alongside other inclusions, so they’re easier to judge. But in lab-grown diamonds, especially older or lower-quality CVD diamonds, clouds sometimes form the only inclusion type listed.
The good news is that most problematic clouds can be spotted in real life or with magnified images and videos. The only real exception is the light-scattering faint cloud we talked about earlier: a rare cloud inclusion only visible under 40x magnification. These tend to show up only above certain color zones within the diamond, where the contrast makes them momentarily visible. In my experience, these kind of cloud inclusions can give you the best deals for an eye-clean diamond.
The key is to never rely on the clarity grade alone. A diamond can be graded VS2 or even VS1 and still look hazy if it has bad clouds. This is especially true when the report comments mention phrases like “cloud not shown” or “clarity grade based on cloud not shown.” These comments are your yellow or even red-flags.
James Allen makes it easy to avoid risky picks by offering high-resolution videos for every diamond. You can check for cloudiness yourself before making a decision. They also offer the largest diamond selection online with some of the most competitive prices in the industry.
That said, not all cloud comments are bad. Regarding lab-created diamond, most modern CVD lab diamonds from reputable vendors don’t suffer from visual haziness anymore, even if the report mentions a cloud. Manufacturing methods have improved a lot and what I call bad clouds are now extremely rare. So if the sparkle looks strong in the video and everything else checks out, you’re probably safe.
If you’re shopping for step-cut shapes like emerald or asscher cuts, be extra careful. These styles show inclusions more clearly than round brilliants because they have broader facets and less sparkle to distract the eye.
For top-tier sparkle, Whiteflash specializes in elite-cut diamonds and clearly marks which ones are eye-clean. If you’re going for maximum performance with complete transparency, they’re hard to beat.
I also recommend checking out Blue Nile’s massive diamond selection if you want extra filtering options and easy side-by-side comparisons, it’s one of the few that nearly rivals James Allen in size and flexibility.
Lastly, always trust your eyes. Use the video, scan the report, look for sparkle and fire. If anything feels off, walk away. You’re not buying a grade, you’re buying how that diamond looks on your finger.