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Do Lab Grown Diamonds Get Cloudy Over Time? What Changes

Do lab grown diamonds get cloudy over time? No. What GIA research says about haze, inclusions, treated colour and grease, and how to pick a clear stone.

No, a lab-grown diamond does not turn cloudy with age. It is diamond, the same carbon crystal as a mined stone, and nothing inside it breaks down from being worn. When a lab-grown diamond looks cloudy, there are three usual reasons: dirt on the surface, inclusions that were there on the day it was polished, or (much more rarely) a stone that was hazy from the start. All three can be checked before you buy.

Why a lab-grown diamond cannot "age" into cloudiness

A lot of the worry comes from simulants. Cubic zirconia can scratch, wear at the facet edges and go dull over the years, and people assume a lab-grown diamond will do the same. It won't, because it isn't a simulant. GIA's consumer guide on lab-grown diamond jewellery says lab-grown diamonds "have essentially the same chemical composition, crystal structure and physical properties as natural diamonds." The US Federal Trade Commission takes the same view in its consumer guidance on buying gemstones and diamonds: lab-created stones "have the same chemical, physical, and visual properties as natural gemstones, but they're manufactured."

So a lab-grown diamond is no more likely to go cloudy than a mined diamond is. Neither one changes inside from ordinary wear, and the inclusions you see on the grading report on day one are the inclusions you'll have in twenty years. A hard knock can still chip a diamond or open a feather, but that applies to mined stones just as much, and it is damage you could point to, not a slow haze.

The most common cause: a film of oil and dirt

Nine times out of ten, when a customer brings in a ring and says the stone has "gone cloudy", the stone just needs cleaning. GIA's guide on how to clean your diamond jewellery points out that "a diamond's sparkle can be lost by the mere touch of a finger." Diamond attracts grease. Hand cream, soap residue and skin oil build up on the pavilion, the underside of the stone that you can't see when the ring is on your hand. That underside is what reflects light back up through the top, so a coating there makes the whole stone look milky.

Here is the routine GIA describes, more or less:

  1. Soak the ring in warm water with a few drops of mild dish soap, or in an ammonia-based household cleaner such as window cleaner. GIA suggests the overnight soak once a week.
  2. Brush it with a soft toothbrush that you keep only for jewellery. Spend most of the time on the back of the stone and around the prongs.
  3. Rinse well. Put the plug in the sink first.
  4. Dry with a lint-free cloth.

GIA warns against chlorine and abrasive cleaners, which can damage the metal setting, though not the diamond. A jeweller can also clean the ring with steam or an ultrasonic cleaner. If the stone looks bright again after cleaning, it never went cloudy in the first place.

Inclusions: "clouds" are a grading term, and they don't grow

The word "cloud" has a specific meaning in diamond grading. GIA's glossary of diamond inclusions defines a cloud as "many tightly grouped pinpoints that might be too small to distinguish individually but together have a hazy appearance." A pinpoint is "a very small crystal that looks like a tiny dot at 10X."

A cloud forms while the crystal is growing, so it is there before the stone is cut and it does not spread afterwards. If a stone looks hazy because of clouds, it looked that way when it left the cutter's wheel.

Where clarity starts to matter for haze

GIA's clarity scale is mostly about whether a trained grader can see inclusions at 10× magnification. Only the bottom of the scale mentions how the stone looks overall. In GIA's words, Included (I1, I2, I3) means "inclusions are obvious under 10× magnification and may affect transparency and brilliance." For SI1 and SI2, inclusions are "noticeable to a skilled grader under 10x magnification." That definition says nothing about haze.

In practice:

  • VVS and VS: a cloud at these grades is too small to affect how the stone looks. You won't see haze.
  • SI1 and SI2: usually fine, but the clarity grade alone won't tell you what kind of inclusion set the grade. An SI2 graded down for one small crystal looks very different from an SI2 graded down for a cloud spread across the table.
  • I1 and below: this is where GIA itself says transparency can suffer. Don't buy one without seeing it.

You don't need VVS to avoid a cloudy-looking stone, and paying for it on those grounds is not worth the money. A well-chosen VS2 or SI1 that has been checked with photos or video will look exactly as clear from across the table.

Lab-grown inclusions are a bit different

According to GIA's guide, HPHT-grown diamonds can contain metallic inclusions from the catalyst metals used in the press, and CVD crystals are "sometimes edged with graphite." These usually show up as dark specks, not white haze. Like natural inclusions, they are fixed at the time of growth.

Haze from inside the crystal: rare, and present from day one

A small number of diamonds look slightly milky even when they are clean and the clarity grade is decent. GIA studied this in its 2021 Gems & Gemology paper on blue fluorescence and diamond appearance (Luo, Nelson, Ardon and Breeding). The authors found that "the 'hazy' appearance that often impacts apparent diamond transparency is mainly attributed to light scattering from structural defects," and that "fluorescence alone does not noticeably reduce transparency." When strong fluorescence and those structural defects occur together, the haze gets worse.

That study looked only at natural diamonds, so it doesn't tell us how often lab-grown stones show this kind of haze. Nobody has settled that question publicly, and you should be sceptical of any seller who quotes you a figure. The useful point is the same either way: this kind of haze comes from the crystal structure, it exists when the stone is cut, and it doesn't develop later.

What about treated colour and colour shifts?

Most colourless lab-grown diamonds on the market today have been treated after growth. GIA's 2024 research update, Laboratory-Grown Diamonds: An Update on Identification and Products Evaluated at GIA (Eaton-Magaña, Hardman and Odake), reports that among CVD-grown diamonds submitted to GIA, about 80% "have been subjected to post-growth HPHT treatment to improve their color grade." Fast CVD growth tends to leave a brown tint, and HPHT treatment removes it.

That treatment affects colour, not transparency. The same paper describes some CVD stones that change colour briefly under strong ultraviolet light or heat, and states that "all photochromic and thermochromic color changes observed in laboratory-grown diamonds submitted to GIA have been temporary and fully reversible, without any permanent or long-term color changes." This is a colour effect seen in the lab, and it is not cloudiness. GIA has not reported it causing a lasting change.

Telling the causes apart

What you seeLikely causeWill it get worse over time?What to do
Stone looked bright, now looks dull or milkyOil and dirt film, mostly underneathOnly if you don't clean itSoak and brush as GIA describes, or have a jeweller clean it
Hazy patch in one area, visible in photos at purchaseCloud inclusionNo, it is fixedChoose a different stone if it bothers you
Whole stone slightly milky, even when cleanLight scattering from structural defects, sometimes with strong fluorescenceNo, it was there from the startCheck video before buying; return or exchange per the seller's terms
Dark specksMetallic or graphite inclusionsNoA clarity question, not a cloudiness one
Brief colour shift after strong UV or heatPhotochromic or thermochromic effect in some CVD stonesGIA reports these as temporary and reversibleLet it sit under normal light

How to choose a lab-grown diamond that stays clear

Since cloudiness is either dirt or something you can see on day one, picking a clear stone is a matter of checking before you buy:

  1. Read the grading report, not just the grade. Look at the plot and the comments line. Watch for "clouds not shown" or a clarity grade where clouds are the main characteristic.
  2. Look at the stone itself. Use the magnified video or high-resolution images when you browse loose diamonds. Haze shows up as low contrast and a greyish, washed-out look across the table.
  3. Be wary of very strong fluorescence in high colour grades. It is usually harmless, but combined with structural defects it can make haze worse, according to the GIA study above.
  4. Pick a setting you can clean. Open galleries and simple prong heads let soapy water and a brush reach the underside of the stone. Some closed or very ornate under-galleries trap grime. You can compare designs in our engagement ring settings.
  5. Disclosure. The FTC says sellers "should disclose if a treatment is not permanent, creates special care requirements for the gemstone, or if the treatment significantly affects the stone's value." Ask if you're unsure.

What to do next

If you're comparing stones, start with the clarity grade and then check the video for any visible haze. A stone that looks clear on day one will stay clear as long as you keep the back of it clean. Search our loose diamond inventory, pair the stone with a setting that's easy to clean, and preview the finished ring in 3D before you finish the ring with metal, size and engraving. For more on clarity and grading reports, see the other guides on our blog.

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