How scientists cracked the secret to making diamonds

Hey, smart people,

This story delves into the centuries-long pursuit by scientists to understand one of the most mysterious substances in the universe: diamonds. These minerals are so tough that only another diamond can scratch them.

It’s the story of how scientists unraveled the secrets within these crystals and figured out how to replicate the extreme temperatures and pressures that once only existed deep within the Earth, making it possible to create diamonds in the lab.

Today, we have exclusive access to a lab where diamonds are made, showing you something very few people ever get to see: how this lab turns one of the universe’s most valuable and resilient materials into diamonds from the remains of loved ones.

Humans have been using diamonds since at least 2500 BCE, when the ancient Chinese used them to polish stone tools. Our fascination with these remarkable crystals likely goes back to the first time one was pulled from the earth.

•Just imagine digging through the dirt and discovering this clear, shiny material. It never rusts, never fades, and essentially lasts forever—which is the cornerstone of diamond marketing: “diamonds are forever.”

Despite their enduring nature, the chemical composition of diamonds is identical to graphite, the material found in pencil leads—famous for its impermanence. So what makes a diamond, well, a diamond?

•It all comes down to how it’s formed. The pressure and temperature under which carbon forms determine whether it turns into a lump of coal that crumbles in your hands or the hardest material known to man: shiny, beautiful, and resilient diamonds.

Here at this lab, they’ve perfected the process of transforming carbon into diamonds, with carbon sourced from an unexpected place.

•In our case, it comes from the loved ones of our customers. We can grow diamonds from their ashes, creating a beautiful, wearable memorial for them to carry wherever they go. My friend Joe passed away from ALS about a year ago, so we’re growing diamonds for his wife, daughters (my goddaughters), and for me as well.

•That’s incredibly special. I’m eager to see how this works.

•Absolutely.

Before we dive into that process, let’s first appreciate how incredible it is that we humans can even create diamonds. Before the 20th century, all diamonds on Earth were formed naturally.

Up until the 18th century, no one even understood what diamonds were. You couldn’t make them, you couldn’t destroy them—they simply existed. But one day, thanks to a fortunate experiment, they didn’t.

In the late 1600s, scientists in Florence were experimenting with diamonds, heating them using a lens that focused sunlight. They hoped that destroying them would reveal something about their nature. But what they found shocked them.

The diamond didn’t melt or turn to dust—it simply disappeared. In the 1770s, French chemists tried similar experiments and found the same thing: when heated, diamonds would vanish without a trace.

It seemed like if you heated a diamond enough, you could destroy the most indestructible material on Earth. These experiments helped solve one of the oldest mysteries in chemistry: the true nature of diamonds.

To explain this, I reached out to my friends from the “Reactions” channel, who know a lot about chemistry—and a lot about burning things.

•I do love chemistry.

Here, we have small but beautiful diamonds inside a quartz glass tube. I’m running pure oxygen over them to help them burn. At first, nothing happens, but then the diamonds start to glow, and they shrink, burning away.

Then something surprising occurred: the diamonds shrank enough that they were carried away by the stream of oxygen. This is chemistry at its finest, where things rarely work on the first try. So I stopped, lowered the flow, and tried again.

Then something even more fascinating happened: some of the diamonds were jolted by the oxygen flow and seemed to disappear before our eyes. Watch this one, this one, and this one.

Diamonds vanish only when heated in the presence of oxygen. So what’s happening here?

•At first, French scientists thought they were left with nothing, but when they collected the gas released from the vaporized diamonds and bubbled it through a calcium solution, it turned cloudy.

This was strong evidence that the gas released by the burning diamonds was simply carbon dioxide. The scientists had figured it out: the diamonds were burning, and the material being released was reacting with oxygen to form carbon dioxide.

And what do you need to create carbon dioxide? Carbon—an unexpectedly simple answer. The same carbon found in pencil lead makes up these beautiful, hard crystals.

While scientists had figured out the main ingredient in diamonds, the next challenge was how to replicate the process. Earth does this naturally in its mantle, but how could we recreate it?

To do that, we have to replicate Earth’s mantle conditions—and that’s where this machine comes in.

•That’s right, we’re recreating the Earth’s mantle right here.

•So, this is like an Earth’s mantle machine?

•Exactly!

•Does this look like a million-dollar waffle press?

•Yes, it’s kind of like that. It would definitely flatten your waffles, but it’s designed for a cooking range of around 2,000 degrees.

This is where Abe and his colleagues turn the ashes of loved ones into diamonds. But before that, they need to extract carbon from the ashes, as we’re carbon-based life forms, but not entirely carbon.

The first step involves treating cremated remains with high heat to vaporize elements like phosphorus and nitrogen, leaving behind pure carbon.

•This is all the carbon we get from the ashes. It’s a tiny, precious amount. For example, a one-carat diamond is only 0.2 grams of carbon. So, this is our carbon. This one’s for Joe.

The purified biological carbon is mixed with a special graphite, pressed into a disc, and sandwiched between a metal alloy and a small diamond wafer, which serves as the seed for crystallization.

Now, it’s ready to be transformed into a larger diamond crystal. This process is surprisingly similar to making rock candy.

In rock candy, you dissolve sugar in water and add seed crystals. The sugar molecules precipitate out, stacking on the seed in a specific, repeating pattern to form a solid chunk.

Since carbon doesn’t dissolve in water, it’s dissolved in molten metal at high temperatures instead.

Under extreme conditions, carbon atoms from the ashes and graphite are broken down into individual atoms, forming a metal-carbon solution that will build a new crystal.

Let’s pause to talk about the versatility of carbon.

Carbon can form a variety of stable crystal structures. Graphite, the most common form, has carbon atoms bonded to three others, allowing layers to slide over one another—perfect for lubrication or pencils.

There’s also Buckminsterfullerene and other less common carbon structures. The structure carbon adopts depends on temperature and pressure.

Under the extreme conditions of Earth’s mantle, carbon forms a tight crystal structure, where each atom bonds with four others. This arrangement gives diamonds their incredible strength.

To create this structure, carbon atoms must be squeezed tightly. This is where the machine comes in.

•The pressure here is like placing a Boeing 737 on top of a Post-It note.

•All that pressure is directed at the growth cell. The cell holds the carbon disc with special metals, and it also contains the crucial diamond seed.

•You place a tiny diamond seed, about the size of a grain of salt, with the perfect face up. This seed acts as a template for the diamond to grow on, ensuring an even shape.

•The seed crystal serves as the atomic blueprint for the rest of the diamond.

•Exactly. Once it’s set, the rest of the carbon attaches and builds on the seed, following the same atomic geometry.

•Amazing!

These plates compress and flatten the carbon disc. Once the machine closes, it compresses the material into a pancake shape.

•The growth cell is heated to about 1,400°C and subjected to 55,000 times the pressure we experience on Earth’s surface. This allows the carbon atoms to flow through the metal and deposit onto the seed, forming the diamond’s unique atomic structure.

After a few weeks, the disc is cooled, removed from the press, and the diamond is extracted. After a quick acid bath to dissolve the solidified metal, a raw diamond emerges.

•It’s incredible to watch black carbon powder transform into a brilliant, shiny rock.

•The hardest material on Earth.

•And it came from powder.

This diamond will still need to be cut and polished, but it’s essentially identical to a natural diamond.

The only major chemical difference between lab-grown and mined diamonds is the ratio of carbon isotopes. Organic carbon contains more carbon-14, due to what we consume. Without specialized equipment, even experts couldn’t tell them apart.

And just like that, from death, a diamond is born. This is the diamond we’re making from my friend Joe.

•Yes.

•What’s your final goal for this diamond?

•I’m going for a blue emerald shape and will set it in a golf putter. Joe and I used to golf together all the time, so it’ll be the sight line on the putter.

Today, labs like this are accelerating geological and chemical processes that take eons in nature. Whether a diamond is formed deep in the Earth or in a lab, whether it turns graphite into a precious gem or death into a memory, diamonds show us how remarkable transformations are possible.