Black Diamonds in Fine Jewelry: Lab-Grown vs. Natural, Treated and Coated

In our last blog, we explored the hidden universe of colored diamonds, from fiery yellows to romantic pinks and the rarest reds. Among those shades, one stood out for its bold, almost rebellious character: the black diamond.

Today, I want to take you deeper into its story — what makes a diamond truly black, why some are natural while others are treated, and how lab-grown black diamonds are giving us a chance to enjoy this striking gem in fine jewelry without compromise.

If you haven’t yet read our guide to colored diamonds, I recommend starting there to see how black diamonds fit into the broader spectrum of nature’s rarest treasures.

Black diamonds

Black diamonds are genuine diamonds with a bold, opaque beauty. Unlike clear white diamonds that sparkle with rainbow brilliance, black diamonds absorb most light due to abundant dark inclusions (often graphite) inside the stone. This gives them a mysterious, metallic luster instead of the typical diamond fire. 

Importantly, black diamonds are every bit as “real” as colorless diamonds — whether they come from the earth or a lab, they share the same pure carbon composition and extreme hardness.

What Makes a Diamond Black?

In a word: inclusions. The deep black color isn’t from any dye or coating in a true black diamond – it comes from tiny mineral impurities (like graphite, pyrite, or hematite) and numerous internal fractures within the diamond’s structure. 

https://www.capetowndiamondmuseum.org/

Essentially, a black diamond is so heavily included or combined with other carbon forms that it appears opaque black.

These inclusions distinguish black diamonds from other fancy color diamonds: unlike a vivid blue or pink diamond that gets its hue from trace elements (boron, nitrogen, etc.), a black diamond’s color is due to concentration of inclusions rather than a pure crystal lattice impurity. This also means black diamonds typically have one color grade – “fancy black” – with the most prized being a uniform, rich black tone without patchy areas.

All diamonds, black or not, rank 10 on the Mohs hardness scale, making them the hardest natural substance. Black diamonds are no exception. You cannot scratch a black diamond except with another diamond.

However, the abundance of inclusions means black diamonds can be more brittle in structure than a typical clear diamond. In fact, black diamonds – especially natural ones – often contain micro-fractures that can weaken the stone under hard impact. They’re tough and durable for jewelry, but not indestructible.

Understanding the different types of black diamonds and how they’re made will shed light on their authenticity, durability, and suitability for fine jewelry.

Natural Black Diamonds (Carbonado)

Natural black diamonds, often called carbonado, are the rarest of the black diamonds. They are mined from only a few places in the world (notably Brazil and the Central African Republic) and are geological oddities. 

Rather than a single transparent crystal, a carbonado diamond is typically a polycrystalline aggregate – essentially many small diamond crystals fused together, peppered with graphite and other minerals. This gives them an opaque charcoal or jet-black appearance.

Fascinatingly, some scientists theorize that carbonado diamonds may not be of earthly origin at all. Recent research has discovered osbornite (TiN) within carbonado — a mineral previously known only from meteorites and comets — suggesting these enigmatic diamonds could have formed in space before arriving on Earth [1]. While the extraterrestrial theory is still debated, it adds an undeniable layer of mystery and romance to the allure of natural black diamonds.

Osbornite. https://www.mindat.org/min-3035.html

From a jewelry perspective, untreated natural black diamonds are extremely rare and therefore command high prices in the market. A genuine carbonado with no treatments is prized by collectors. These stones tend to have a dark, porous texture and may be more challenging to cut and polish due to their polycrystalline structure. They do not sparkle; instead, a well-cut carbonado will display a glossy shine on its facets.

Because natural black diamonds are so included, they can have internal weaknesses – jewelers know that a natural black diamond can chip or crack more easily than a clear diamond if struck, despite its hardness. For this reason, you’ll often see experts recommending protective settings (more on that later) for black diamond center stones.

In summary, a natural black diamond is the pinnacle of rarity for this color: a true geological rarity with a distinctive origin story and a bold look, but one that requires careful handling and comes at a steep cost in fine jewelry.

Lab-Grown Black Diamonds

Lab-grown black diamonds are man-made diamonds grown in a laboratory, engineered to have the same characteristics as natural black diamonds. Crucially, these are real diamonds – they consist of pure carbon arranged in the diamond crystal structure, just like mined diamonds.

This means a lab-grown black diamond has the authenticity of a diamond (unlike, say, a simulant like cubic zirconia) and the same inherent hardness and durability. In fact, lab-grown diamonds are just as durable and timeless as natural diamonds, with no risk of “fading” or degrading over time. You can think of them as diamonds with a different origin story: grown by technology rather than by geological processes.

How are lab-grown black diamonds made? Labs can produce diamonds either by High Pressure High Temperature (HPHT) or Chemical Vapor Deposition (CVD) methods. To create a black diamond, scientists replicate conditions that introduce a high amount of inclusions or graphite into the growing crystal. Essentially, they allow the diamond to form with a rich black color inherent to the material (as opposed to adding color later).

Because the growth process is controlled, lab-grown black diamonds often have a very even, uniform black color. They don’t rely on chance inclusions; technicians can adjust conditions to achieve the desired opacity. In many cases, the quality of lab-grown black diamonds is actually quite high – the stone can be more homogeneously black and with fewer surface-breaking flaws than some mined ones. In other words, you might get a smoother, more blemish-free surface on a lab-grown black diamond because it was cultivated under optimal conditions, even though it’s opaque internally.

Lab-grown black diamonds excel in durability for everyday wear. Since they are essentially identical in composition to natural diamonds, they share the same Mohs 10 hardness and resistance to scratching. They will not chip or break easily under normal use – though like any black diamond, if they contain internal inclusions, extremely rough handling could cause issues.

Many engagement ring buyers are drawn to lab-grown black diamonds for their similarity to natural carbonado in looks and performance, without the extreme rarity. Visually, a lab-grown black diamond is virtually indistinguishable from a natural black diamond of the same size and cut. Both are opaque, black, and lustrous – only advanced lab equipment could tell their origin apart.

From a value standpoint, lab-grown black diamonds are far more affordable than natural blacks. Because they are created in a lab, they are not limited by scarcity – this generally makes them the most budget-friendly option among black diamonds. You can often get a larger or higher-quality black diamond for your money by choosing lab-grown. Many eco-conscious or ethically-minded buyers also prefer lab-grown gems, since they bypass the environmental impact of mining (and any ethical issues that might come with mined stones).

In short, lab-grown black diamonds offer authenticity and durability on par with natural black diamonds, at a fraction of the cost. They have become a popular choice for modern fine jewelry that makes a bold statement without breaking the bank.

Treated Black Diamonds

Treated black diamonds occupy an interesting middle ground – they start as natural diamonds, but not black ones. Instead, they are typically low-color or heavily included white/brown diamonds that are artificially turned black through treatment.

The most common method is heat treatment or irradiation: exposing the diamond to high temperatures or bombardment that causes the plentiful inclusions to darken (often by forming graphite) and yield a uniformly black appearance.

Essentially, the treatment “paints” the diamond black from the inside by converting it into a heavily included black stone. These treated diamonds achieve the desired color, but it’s an alteration of nature – unlike a natural carbonado or a purpose-grown black diamond, a treated black was not originally that color.

In terms of appearance, a treated black diamond can look nearly identical to a natural black or lab-grown black to the naked eye: opaque and black. The color treatment is typically permanent and stable (the diamond will stay black; it won’t fade under normal conditions). For example, irradiation and HPHT treatments used on diamonds produce a lasting black color that can withstand regular wear.

From a durability standpoint, treated black diamonds still have the inherent hardness of diamond (they’re a real diamond, after all). However, remember that these stones were chosen for treatment because they were heavily flawed to begin with. They usually contain many fractures and inclusions (that’s why they could be turned black), which means their structural integrity is not as sound as a higher-quality diamond.

In practice, a treated black diamond can be more prone to chipping if struck sharply, as those internal flaws create weak points. Jewelers often handle treated blacks with care, avoiding aggressive polishing or ultrasonic cleaning that might exploit a crack.

The big advantage of treated black diamonds is cost. They are much less expensive than natural black diamonds because they start from relatively common, lower-grade material. In fact, treated blacks are often even cheaper than lab-grown diamonds. As one source notes, most black diamonds on the market are heat-treated and incredibly affordable – often sold for only a small fraction of the price of an equivalent natural black diamond [2]. This makes them accessible for fashion jewelry and for consumers who want the dramatic look without a high price.

However, the trade-off is value and honesty: a treated black diamond has very little resale value (once a diamond is revealed to be treated, its value drops dramatically, on the order of 90% less than a comparable natural black). For this reason, any reputable seller will clearly disclose the treatment.

Treated diamonds can absolutely be used in fine jewelry – many designers use treated black melee (small diamonds) in pavé settings or as accents – but they should be marketed as “color-enhanced” diamonds. They offer the black diamond aesthetic at a low cost, but they are considered less desirable for investment or heirloom pieces.

If buying one, make sure you’re comfortable with the fact that it’s an enhanced stone and that you’re not paying a premium for what is essentially a common diamond that’s been “painted” black by science.

Coated Black Diamonds

Coated black diamonds are the least common and least desirable category of all – in fact, some purists wouldn’t even consider them true black diamonds. A “coated” black diamond means that the stone’s black color comes from a surface treatment only, not from the diamond’s actual body color.

For example, a diamond (which might be colorless or brownish) could be coated with a thin layer of black material – such as paint, ink, or a metallic oxide film – to give it a black appearance [3]. This is analogous to taking a white diamond and essentially coloring its surface black. While this can produce a convincingly black look initially, the approach is fundamentally a cosmetic trick and not permanent.

Thin-film coatings on gems are known to be fragile: they often do not bond strongly to the diamond’s ultra-hard surface, so the coating can scratch or wear off over time [3]. Edges and facet junctions are especially vulnerable – a small scratch at the surface can reveal the diamond’s true lighter color underneath, ruining the black illusion [3].

Coating a diamond is generally viewed as a misleading practice if not properly disclosed. Because a coated diamond is still a diamond, unscrupulous sellers might try to pass it off as a natural black diamond to unwary buyers. However, gemological labs can detect coatings easily under magnification or spectroscopy (for instance, GIA reported uncovering a coated black diamond that had been presented as natural black [4]).

In fine jewelry, you typically do not want a coated stone – not only because of honesty, but also the longevity. Imagine wearing a black diamond ring daily and after a year, the black coating starts chipping, exposing a dull grey or white patch! It’s not a durable or elegant solution.

Thus, coated black diamonds are usually confined to the very low end of the market or novelty costume jewelry. If you encounter a “too good to be true” cheap black diamond, especially in online marketplaces, be cautious – it could be a coated stone.

In summary, coated diamonds should be avoided for engagement rings or fine jewelry, as the coating is not permanent and the practice is considered deceptive unless clearly disclosed.

Identifying High-Quality Lab-Grown Black Diamonds (and Other Buying Tips)

When shopping for a black diamond – particularly a lab-grown black diamond – you’ll want to know how to spot quality and ensure you’re getting exactly what you expect. Here are some key tips:

• Color and Uniformity: The best black diamonds show a deep, pure black color that looks consistent from edge to edge. Examine the stone under good light: a high-quality lab-grown black should not have pale spots, brownish tints, or uneven “blotchy” areas. Because black diamonds absorb light, they won’t sparkle, but you should still see a nice glossy surface luster. Opaque does not mean dull! Avoid stones that look mottled or have visible lighter inclusions showing through – a uniform inky black is ideal.
  
  
• Cut and Surface Quality: Even though you can’t judge black diamonds by the traditional clarity grade (they’re all opaque), cut still matters. A well-cut black diamond will have symmetrical shape and a smooth polish, which gives it that mirror-like shine. Check the surface under magnification if possible. High-quality lab-grown blacks tend to have fewer surface-reaching fractures because of controlled growth, but you should still inspect for chips or pits. If you see many tiny pits or lines on the surface (inclusions breaking the surface), that stone might be more prone to chipping. One expert tip: avoid black diamonds with numerous surface inclusions or cracks – those are “risk points” for breakage. A clean, well-polished surface is a sign of a sturdier black diamond.
  
  
• Durability and Setting: All black diamonds, natural or lab, are hard enough for daily wear. But due to their internal structure, consider opting for protective jewelry designs. Bezel settings, which encircle the diamond’s edge with metal, are often recommended for black diamond rings that will be worn frequently. A bezel (as opposed to prongs) shields the diamond’s edges and helps prevent chipping if the ring is knocked. Halo designs (a ring of small diamonds around the center) can also offer some protection and emphasize the stone. Also, be gentle with cleaning – stick to mild soap, warm water and a soft brush. Avoid ultrasonic cleaners or sudden temperature changes, since black diamonds can have inclusions that expand with heat (thermal shock could conceivably cause cracks in heavily fractured stones). With sensible care, a lab-grown black diamond will maintain its bold appearance for a lifetime.

Serena. Bezel Setting

Certification is key when buying a black diamond. Reputable jewelers will provide an official lab report identifying the stone’s characteristics. Unlike colorless diamonds, a black diamond’s certificate won’t list a clarity grade or traditional color grade (it will simply say “Fancy Black”).

However, the report should explicitly state the diamond’s origin (natural or laboratory-grown) and whether any treatments were applied. This documentation is crucial for trust and value – it ensures you know if the gem is untreated, heat-treated, or otherwise enhanced. For lab-grown black diamonds, a certificate from a respected gemological lab like IGI or GIA provides peace of mind [5].

The IGI (International Gemological Institute), for example, is well-known for accurate grading of lab-grown diamonds. Their reports will confirm that your black diamond is lab-created and note if it’s naturally colored or treated.

Obtaining an IGI or GIA certificate is also the best way to avoid unwittingly buying a treated or coated stone sold as something else. In short, always buy from a trusted jeweler and insist on certification – it’s your insurance that you’re getting a high-quality black diamond of the type you desire.

Value and Choosing the Right Black Diamond

When comparing black diamond options, it helps to understand the value positioning of each type.

Natural untreated black diamonds sit at the top of the value pyramid due to their rarity – they are the most expensive per carat and often purchased for their uniqueness and collectors’ appeal.

Lab-grown black diamonds offer the best bang for your buck: you get an authentic diamond with the same look and durability as a natural black, but generally at a significantly lower price point (often 30-40% less cost than a comparable natural stone).

Treated black diamonds are usually even more affordable, as their abundance in the market keeps prices low. These can be a smart choice if you want a big, dramatic black stone purely for its aesthetic and are less concerned about long-term value or origin.

Coated black diamonds are not considered a wise purchase for fine jewelry – any initial savings quickly lose appeal if the coating gets damaged, and they have essentially no resale value.

Which should you choose?

That depends on your priorities. If you love the idea of a stone forged in nature over billions of years (or possibly in outer space!), and you don’t mind the premium, a natural black diamond has an unbeatable rarity factor. Just be sure it comes with a gem lab report verifying it’s natural and untreated, since you’re paying for that rarity.

If instead you want the look of a stunning black diamond engagement ring without spending a small fortune – or you prefer a diamond with a guaranteed ethical origin – a lab-grown black diamond is an excellent choice. It will be genuine, durable, and far more budget-friendly, allowing you to maximize size or save money for the setting.

Treated black diamonds can work for fashion jewelry or if you’re on a tight budget, but remember that you’re essentially buying a heavily included diamond that’s been color-enhanced. There is nothing wrong with that as long as the price reflects it (it should be much cheaper) and the seller is transparent.

Coated diamonds, in contrast, are best avoided for any significant piece of jewelry – the risk of the color wearing off makes them unsuitable for something like an engagement ring intended to last generations.

Final Thoughts

Black diamonds have emerged as a compelling choice for those seeking a non-traditional yet sophisticated statement in fine jewelry. From the exotic natural carbonado to the innovative lab-grown versions, these stones offer an alluring combination of mystery and strength.

The Black Orlov

A black diamond engagement ring, for example, radiates individuality and modern style – a true conversation starter. Lab-grown black diamonds, in particular, allow buyers to enjoy this bold look with confidence in the stone’s authenticity and durability, mirroring the qualities of natural black diamonds without the steep cost or ethical uncertainties.

Meanwhile, understanding the differences in how black diamonds are created arms you with knowledge: you now know why a lab-grown or natural black diamond is preferable to a treated or coated one if you value longevity and true value.

In the end, choosing a black diamond comes down to personal preference – but it should be an informed choice. Whether you’re drawn to the rarity and lore of a natural black diamond or the affordability and consistency of a lab-grown stone, insist on transparency about the gem’s origin and treatments. With the right information (and a trusted certification in hand), you can select a stunning black diamond piece that will endure beautifully over time.

Authentic, enduring, and undeniably striking, black diamonds – especially lab-grown black diamonds – are making their mark in the world of engagement rings and high-end jewelry, proving that not all diamonds shine bright to steal the spotlight. They do it in their own dark and dramatic way, and for many, that makes them all the more desirable.

References

[1] G. Parthasarathy, “Carbonado-diamond is the most enigmatic of all the known high pressure carbon polymorphs,” American Geosciences Institute Open Collections, International Geological Congress, 2021. Available: https://information.americangeosciences.org/open-collections/igc/1486/

[2] Estate Diamond Jewelry. Complete Guide to the Black Diamond. Available: https://www.estatediamondjewelry.com/guide-black-diamond/

[3] GIA, Gemstone Treatments: Coatings. Available: https://www.gia.edu/gem-treatment

[4] GIA, Fall 2011 Gems & Gemology Lab Notes. Available: https://www.gia.edu/doc/Fall-2011-Gems-Gemology-Lab-Notes.pdf

[5] IGI, Lab-Grown Diamond Certification. Available: https://www.igi.org/