- Hey smart people, Joe here.

This is a video about scientists centuries long quest to understand one of the most mysterious materials in the universe, diamonds.

A mineral so strong it can only be scratched by another diamond.

It's the story of how scientists uncovered the secrets inside these crystals and how they learned to replicate the extreme temperatures and pressures once only found deep inside our planet to achieve what was once unthinkable, making diamonds in the lab.

Today we've been given exclusive access to a lab that manufactures diamonds to show you what almost no one gets to see, how this lab makes some of the most valuable and most resilient materials known in the universe out of dead people.

(bright music) Humans have been using diamonds since at least 2500 BCE when the ancient Chinese use them to polish stone tools.

it's likely our obsession with these strange crystals goes back to the first time we pulled one out of the dirt.

- I mean, imagine digging through the earth and you find this clear, shiny material in the ground.

I mean, it never rusts, it never goes away.

It basically lasts forever, which is the marketing campaign of natural diamonds is, diamonds are forever, right?

- Despite this, the chemical ingredients within a diamond are identical to those found in pencilled, a material that's famous for how impermanent it is.

So what makes a diamond a diamond?

- And it's all about the way that it's formed, the pressure and the temperature that that carbon forms under results in whether it's a lump of coal and you can crumble it in your hands, or if it's the hardest material known to man and it's shiny and bright and beautiful.

- Here at this lab they've mastered that process of turning carbon into diamonds and that carbon comes from a surprising source.

- In our case, it comes from the loved ones of our customers, and we're able to grow a diamond from that encapsulating this beautiful memorial that they can wear with them and have a bright shining memorial of their loved one wherever they go.

My friend Joe passed away from ALS about a year ago, so we're growing diamonds for his two daughters which are my goddaughters, as well as his wife and for myself.

- That's really special.

I mean, I wanna see how this is done.

- Absolutely.

- Before we take a look at that process, we've gotta talk about how insanely cool it is that we humans can make diamond gemstones at all.

Because before the 20th century, all the diamonds on earth were made by earth.

And as recently as the 18th century, no one could even figure out what diamonds actually were.

You couldn't make them, you couldn't destroy them, they were just there, until one day, thanks to a lucky experiment, they weren't.

In the late 1600s, a couple of scientists in Florence were experimenting with heating diamonds by using a lens that focused the sun's rays.

They hoped destroying it would tell them something about diamonds underlying nature.

They made a shocking discovery.

The diamond didn't melt or turn into powder or anything, it just vanished.

Later in the 1770s, French chemists were sticking diamonds under lenses or into crucibles and furnaces, and they found the same thing.

Over and over again the heated diamonds just disappeared without a trace.

It seemed like if you could get a diamond hot enough, you could destroy the most indestructible material on earth.

These surprisingly simple experiments would help solve one of chemistry's oldest mysteries about the true nature of diamond.

To show you how it works, I called my friends from the channel "Reactions" who know a thing or two about chemistry and a lot about burning things.

- It's true, I do love chemistry.

(burner blazing) These are some very small, but very pretty diamonds in a quartz glass tube, and I'm running a stream of pure oxygen over them 'cause that'll help them burn.

At first, not much happens, but then the diamonds start to glow and slowly the diamonds got smaller and smaller and smaller as they burned away, and then something happened that I did not expect.

They got small enough that they were carried away by the stream of oxygen gas, because this is chemistry where it literally never works on your first try.

So I had to stop the experiment, lower the flow and try again, and then something even cooler happened.

Some of the diamonds got buffeted around in the stream of oxygen and you can actually see them wink out of existence.

Like, look at this one and this one, and then this one.

Now the diamonds only vanish if they're heated in the presence of oxygen.

So the question is, what's going on here?

- Now, at first glance, the French scientists thought they were magically ending up with nothing where there used to be something.

But when they collected the gas coming off of the vaporized diamonds and bubbled it through a solution of calcium dissolved in water, it turned cloudy.

This was strong evidence that the gas released by vaporizing diamonds was simple carbon dioxide.

So now the scientists had a pretty good idea of what was going on.

The diamonds were burning and the material coming off of them was reacting with oxygen in the air to create carbon dioxide, and what do you have to add to oxygen to get carbon dioxide?

Carbon, a simple and surprising answer.

The exact same stuff that makes up graphite in a pencil is the soul ingredient in these hard and beautiful crystals.

But even though scientists had pinned down the single ingredient in the recipe for diamonds, that still left the problem of how to cook one up.

Our planet does this all the time, deep in the mantle.

But how exactly do you turn carbon into this instead of this?

So you've gotta recreate earth's mantle in order to make a diamond and that happens in here.

- That's correct, that's happening right in here.

- So that's an earth's mantle machine.

- Let's go.

- I like that.

So is this what a million dollar waffle press looks like?

(both laughing) - Yeah, something like that.

This will definitely press your waffles pretty flat.

- A little overdone for my taste, I don't like them quite that dark for like the 2,000 degree cooking range.

And this is where Abe and his colleagues turn the ashes of dead people into diamonds.

But before they can do that, they need to get the carbon out of those ashes because we're carbon based life forms, but we're not all carbon.

And the first step is to treat cremated remains under high heat to vaporize other elements like phosphorus and nitrogen, leaving pure carbon behind.

- You can see this is all the carbon that we get out of the ashes.

So it's not very much.

When you get in that super purified form, you're just getting a tiny precious amount left over.

If a one carat diamond is only 0.2 grams of total carbon.

So what we get is our carbon, this one is Joe right here.

- This pure biological carbon is mixed with a special form of graphite and squeezed into this disc.

That disc is sandwiched with a special metal alloy and a wafer containing a tiny diamond that will act as the seed for crystallization.

It's now ready to be transformed into a larger diamond crystal.

The process is surprisingly similar to growing rock candy out of sugar.

To do that, you just stick a few seed crystals into water saturated with dissolved sugar.

The sugar molecules will naturally start to precipitate out of the solution and stack on top of the seed crystal in a very specific repeated geometry until you have a chunk of rock candy.

But carbon doesn't dissolve in water.

To make a solution of carbon, it's heated to high temperatures and dissolved into molten metal instead.

At these extreme conditions, the carbon in the ash and graphite is ripped into single atoms, creating a solution of metal and loose carbon building blocks that can form a new crystal.

Let's talk for a second about different things carbon can do.

(upbeat music) Carbon can actually assemble itself into many stable crystal structures.

Graphite is the carbon crystal formed most easily here on Earth's surface, and that's where each carbon atom is bonded to three other carbon atoms allowing different layers to slide past one another, which is why graphite is ideal for lubrication and pencils.

There's also Buckminsterfullerene and other less common carbon crystal structures.

Which form carbon takes depends on which structure is most stable under the given temperature and pressure.

At the extreme temperatures and pressures found in earth's mantle, carbon is most stable in a really tight crystal geometry where each atom is bonded to four other carbons.

This incredibly strong atomic arrangement is what gives diamonds their resilience.

And to create that structure, you need to give carbon atoms a serious squeeze.

That's where this machine comes in.

- The amount of pressure in here is like taking a Boeing 737 jet and resting on a post-it note.

- [Joe] All that pressure is directed onto this growth cell.

The growth cell holds the carbon disc sandwich with special metals, heated and squeezed to dissolve the carbon, and it also contains one other key ingredient, a diamond seed.

- You put a tiny little diamond seed.

It's the size of like a grain of salt, and you have to get that seed with the right face up.

You want a nice perfect little square that acts as your template for the diamond to grow from so that you get a nice even shape.

- This little seed crystal acts almost like an atomic blueprint for the rest of the crystal.

- That's right.

- It's like, we've started building it this way.

We're gonna give you the directions and then all the rest of the carbon that continues to attach to that in a larger form is gonna have the same geometry down to the atomic level.

- Correct.

- Wow!

- These two plates right here, your growth cell is gonna go right in the middle.

When this closes, it's actually gonna compress and flatten that ring and turn it into a pancake.

- [Joe] The growth cell is heated to nearly 1400 degrees Celsius and squeezed at 55,000 times the pressure we feel here on Earth's surface, allowing free carbon atoms to flow through the metal and deposit onto the seed crystal, enlarging the diamond's unique atomic geometry.

And after a couple weeks, the disc is cooled, pried out of the press and the diamond removed.

After a short bath in acid to dissolve the solidified metal, a raw diamond emerges.

- Yeah, it's very cool to see that black carbon powder that you saw in the other room become this shiny brilliant rock, right?

- Hardest material on earth right there.

- Absolutely.

- Out of powder.

This diamond still needs to be cut and polished, but it's essentially identical to a natural diamond.

One of the only chemical differences between a diamond like this one and most diamonds mined from the earth, is the ratio of carbon isotopes.

Since organic carbon holds a higher ratio of carbon 14 due to what we eat.

Without specialized tools, even an expert couldn't tell the two apart just by looking at them.

And just like that, from death emerges a diamond.

The diamond you're getting made from your friend, Joe.

- Yeah.

- What's the the final goal for that diamond?

- So I'm doing a a blue emerald shape and I'm actually gonna set it into a golf putter.

He and I used to golf all the time, and I'm gonna set it as the sight line on the putter.

- Today labs like this are speeding up fundamental processes of geology and chemistry that have been going on for eons on our planet and well anywhere in the universe where we find carbon, heat and pressure.

Whether a diamond comes from the belly of the earth or a lab and whether it's turning graphite into a precious gem or death into a memory, the resiliency of diamonds shows what amazing transformations are possible on our planet, stay curious.