What Are Black Diamonds? Natural, Treated, and Lab-Grown

Black diamonds are real diamonds, made of carbon and just as hard as white diamonds at a 10 on the Mohs scale. The three types get their black color from different sources: graphite trapped inside a natural stone, heat or radiation that darkens a white diamond, or defects built into a lab-grown crystal. All three are real diamonds, but the type changes the grading, the value, and the resale.

 

The three kinds of black diamond

Every black diamond is the same material at heart: carbon, crystallized under heat and pressure. White diamonds look clear because light passes through them cleanly. Black diamonds look dark because light gets trapped or absorbed inside. The cause of that darkness is the whole story, and it sorts black diamonds into three groups. You can browse all three in our black diamond engagement rings.

 

Natural black diamonds (and carbonado)

Natural black diamonds form deep in the earth, the same way every mined diamond does. What sets them apart is what is trapped inside. As GIA explains, their color comes from a high number of tiny dark inclusions, mostly graphite, plus minerals like hematite and pyrite. Old cracks inside the stone also stain dark over time. Under all of that, the diamond's true body color is often near-colorless, brown, or a dark olive green. The inclusions are what your eye reads as black.

Natural black diamonds are usually opaque, with a bright, almost metallic shine called luster. They are rarer than colorless diamonds and harder to cut, so they cost more than treated or lab-grown stones. You may also hear the word "carbonado." That is a separate, rare kind of natural black diamond. It is made of many tiny crystals fused together, a structure called polycrystalline, and it is found mostly in Brazil and Central Africa. Carbonado is tough and porous, so it is used more in industry than in rings.

Treated black diamonds

Most black diamonds in jewelry are treated, not naturally black. A treated black diamond starts as a real white or gray diamond. It is usually one that is so included or cracked that it would never make a clear gem. Heat or radiation then turns it dark. The result is a real diamond with an even, dramatic black color at a lower price.

There are two common methods. The first is high-temperature heating, called annealing. It turns the tiny cracks inside the stone to graphite, which makes the diamond look black. The second is irradiation, which shifts the color to a green so deep that it reads as black. Treated diamonds are not radioactive and are safe to wear. The catch is value. Treatment lowers the price a lot, so you want to know about it before you buy. Our GIA-certified diamonds spell out exactly what you are getting.

Lab-grown black diamonds

Lab-grown black diamonds are grown in a lab in a few weeks. They use the same two methods that make every lab diamond: HPHT and CVD. They share the chemistry, crystal structure, hardness, and shine of a mined diamond. The color usually comes from a very high number of tiny defects packed into the crystal, which soak up light. Compared with natural stones, lab-grown blacks tend to look smoother and more even in color. They are also the most affordable of the three. For the deep dive on how the two growth methods differ, see our HPHT vs CVD guide, or browse the lab-grown engagement rings.

Why each kind looks black

A white diamond is see-through, so why is a black one not? In a clear diamond, light travels through the stone and bounces back out as sparkle. In a black diamond, the light runs into something inside and gets absorbed instead. What that something is changes from one type to the next, as our diamond color chart helps explain.

In a natural black diamond, the light-blockers are inclusions. The stone is packed with countless specks of graphite and other minerals, and old fractures inside it have stained dark. Each speck absorbs a little light. Together they make the whole stone read as black, even though the diamond around them may be nearly colorless.

In a treated black diamond, people create the light-blockers on purpose. Heating the stone turns its internal cracks into graphite, the same dark material that colors natural blacks. Irradiation works a different way: it changes how the crystal absorbs light until the color deepens to a green so dark it looks black. Either way, the starting white diamond ends up unable to pass light through.

In a lab-grown black diamond, the light-blockers are built in during growth. Growers push the crystal to form with a very high density of tiny defects and dark inclusions. Those defects do the same job as graphite in a natural stone. They scatter and soak up light, so the finished diamond looks evenly black from edge to edge.

How GIA grades and reports a black diamond

Black diamonds are graded differently from clear ones, and this trips up a lot of buyers. A normal diamond report lists the 4Cs, including a clarity grade based on the tiny marks you can see inside the stone under magnification. A black diamond is opaque. You cannot see into it, so a standard clarity grade does not apply. GIA grades black stones as fancy-color diamonds instead, and the report looks different as a result.

For a black diamond, GIA issues a colored diamond report rather than a normal grading report. The color grade reads "Fancy black." Black is a special case among fancy colors. Most fancy colors come with a range of tone and saturation, like Fancy Light or Fancy Vivid, but black is simply black, so it does not carry those extra steps. The report also states the color origin, which is the line that matters most. It tells you whether the color is natural or treated.

That one line settles the question that the stone itself will not answer. A polished black diamond hides its origin well, so the paperwork does the work your eyes cannot. Lab-grown black diamonds get their own report that identifies them as laboratory-grown and notes the growth method. Whatever the type, buy stones with a report and read the color-origin line first. You can shop GIA-certified diamonds so the question is already answered.

How to tell natural, treated, and lab-grown apart

You usually cannot tell these three apart just by looking. A polished black stone hides its origin, which is why the report matters more here than with most diamonds. A few clues help, but only the paperwork is proof. The table below sums up the differences, and you can compare any stone against our black diamond rings as you go.

What to check	Natural	Treated	Lab-grown
Cause of color	Graphite & mineral inclusions	Heat or radiation on a white diamond	Defects added during growth
Crystal type	Single crystal (carbonado is polycrystalline)	Single crystal	Single crystal
What the report says	"Natural" color origin	"Treated" color origin	"Laboratory-grown"
Look	Slightly uneven, textured, metallic	Even, dark, glossy	Very even and smooth
Rarity	Rarest	Common	Made to order
Price per carat	Highest	Lowest	Low, with even color

The visual clues are soft, not proof. Natural stones often show a little texture and an uneven, metallic glow, while treated and lab-grown stones look more even. A skilled cutter can make any of them look clean, though, so your eyes are not enough. Under a loupe, a jeweler can sometimes spot graphite trails in a treated stone, or tiny crystals in a natural one, but even that is rarely the last word. The sure test is the report. Buy a stone with one, read the color origin first, and you have your answer. You can shop black diamond earrings the same careful way.

What black diamonds cost

Price tracks origin, not quality, because all three types are real diamonds. Treated stones give you the black look for the least money, but the treatment caps their long-term value. Natural black diamonds are the rarest, so they carry the highest price per carat and the strongest resale standing. Lab-grown blacks sit in between, with the most even color for the money. Natural black diamond rings in our own black diamond collection start around $650, so the gap is smaller than many buyers expect.

Color is one place lab-grown makes stepping up easy, since even color comes built in. For the full price math on lab versus mined, including how cost per carat changes with size, see our cost per carat guide. Whichever type you choose, a report protects what you pay, because it confirms you are buying the origin you think you are.

What black diamonds mean (meaning and history)

For most of history, people ignored black diamonds. They were seen as industrial material, not gems. One writer in 1928 said the ordinary black diamond was "not greatly unlike black sealing wax." Tastes changed late in the 20th century, when designers began pairing black diamonds with small white diamonds for contrast. Today they read as a confident, modern choice, and you can see that shift in our black diamond engagement rings.

A few famous stones carry the legend. The 67.50-carat Black Orlov, also called the Eye of Brahma, was said to be taken from a statue in India and rumored to be cursed, so it was recut to break the hex. In 2022, a 555.55-carat natural black diamond called The Enigma sold at auction for millions, the largest cut diamond of its kind. In meaning, black diamonds stand for strength and resilience. They form under pressure and endure despite their inclusions, which makes them a natural symbol of getting through hard things. They also simply look bold, which is why they appeal to anyone who wants a ring that stands apart.

When each kind makes sense

Once you know what you are holding, the choice gets simple, and it usually comes down to budget and meaning. Here is the short version, with the full walkthrough in our black diamond buying guide.

• Choose natural if origin and rarity are the point. It formed in the earth, no two are quite alike, and it carries the story and resale standing of a mined stone. You can see certified options among our natural diamond rings.
• Choose treated if the black look at the lowest price is what you want, and you are fine with the value cap. Just make sure the report says "treated" so there are no surprises later.
• Choose lab-grown if you want even color and the most stone for your money. It looks just as black, carries full certification, and frees up budget for size or setting. Compare the lab-grown rings to see the range.

Frequently Asked Questions (FAQ)

The questions buyers ask our consultants most about black diamonds and what they really are.

Are black diamonds real diamonds?

Yes, black diamonds are real diamonds. They are made of carbon and have the same crystal structure and the same 10 on the Mohs hardness scale as white diamonds. The only real difference is the color, which comes from heavy inclusions or from treatment. You can see certified examples in our GIA-certified collection.

What gives a black diamond its color?

The color comes from inside the stone, where something blocks light instead of letting it pass. In natural blacks, dense graphite and mineral inclusions absorb the light. In treated blacks, heat or radiation creates the dark color. In lab-grown blacks, defects added during growth do the work. Our color guide explains how diamond color works overall.

How does GIA grade a black diamond?

GIA grades black diamonds as fancy-color stones, not with a normal clarity grade. Because the stone is opaque, you cannot see inside it, so the usual clarity scale does not apply. The report lists the color as "Fancy black" and states whether the color is natural or treated. That color-origin line is the part to read first. Browse stones that come with it in our black diamond rings.

How can you tell a natural black diamond from a treated one?

A lab report is the only sure way. Natural stones often show a little texture and an uneven, metallic shine, while treated and lab-grown stones look more even, but a good cut hides those clues. A GIA colored diamond report states whether the color is natural or treated in plain words. Always buy a black diamond with that paperwork, like the ones in our GIA-certified diamonds.

Are black diamonds rare?

Natural black diamonds are genuinely rare, rarer than colorless diamonds, which is why they cost the most per carat. Most black diamonds you see in jewelry are not natural, though. They are treated white diamonds or lab-grown stones, both of which are common and far easier to find. The report tells you which one you are looking at. See real natural and lab-grown options in our black diamond collection.

What is carbonado?

Carbonado is a rare, natural kind of black diamond. It is made of many tiny diamond crystals fused into one tough, porous mass. It is found almost only in Brazil and Central Africa, and scientists still argue about how it formed. Because it is so rough and tough, carbonado is used mostly for cutting tools and drills, not rings. Most black diamond jewelry uses single-crystal stones instead, like those in our lab-grown rings.

Are natural or lab-grown black diamonds worth more?

Natural black diamonds are worth more, because they are rarer and carry the story and resale standing of a mined stone. Lab-grown blacks cost less and offer the most even color, which frees up budget for size or setting. Neither is better in quality, since both are real diamonds with the same hardness. For the full decision, see our black diamond buying guide.