As we all know, diamonds are the hardest material we can find on planet Earth. They’re also one of the most valuable available commodities, capturing the minds and souls of humans as soon as they were first discovered and causing more than a few wars throughout history.
As far as we know, the deposits of diamonds are finite, and although new mines are opened every now and then, there will come a day when this well of fortune will eventually dry up. That makes the history of diamonds very exciting – often bloody, entirely palatial, and, unfortunately, finite.
But, where does this history start? How are they formed, can they be artificially produced, and how did people find diamond deposits in the first place? We’ll try to answer all these questions in the following article.
So, fasten your seatbelts, we’re taking off to the place where it all started!
The Chemical Properties of Diamonds and the Difference Between Diamonds and Coal
In order to do that, we’ll need to take a short chemistry class and see what the diamonds’ building blocks are. You know how some people say that diamonds are made of coal?
This common belief was perpetuated for centuries now through literature, movies, and other available media. For instance, in one of the scenes from Superman III, the titular Kryptonian takes the lump of coal, uses his super strength, and crushes it into a beautiful diamond.
Of course, we can wholeheartedly say that all these claims are 100% false. But, people who originally started the chatter were on the right track.
Namely, both diamonds and coal are at their base different forms of the chemical element carbon. You can find it under the big letter C in the periodic system of elements.
The biggest difference between the two materials comes from the purity of these two forms of carbon. In their essence, diamonds are entirely pure carbon turned into their crystalline form. These pure-carbon diamonds are 100% transparent and hold the highest value.
The diamonds with some lesser impurities usually hold some hue – or they are slightly milky and murky – and as you can guess, they’re not as valuable as their pure-carbon brothers.
Speaking in more chemical terms, a natural carbon atom features the nucleus made up of six protons and six neutrons, balanced out by six electrons.
Diamonds are made from repeating units of atoms joined to four other carbon items through the covalent bonds, which are the strongest possible chemical bondage.
Together they form a firm tetrahedral network (a molecule cube) which lends diamonds their legendary endurance.
In the picture above, we can see the molecular structure of diamonds compared to some other carbon-based materials. It looks sharp, pure, precise, and essentially rock-solid.
Coal, on the other hand, is an entirely different beast. Sure, this material is carbon-based but in this case, the material includes large quantities of other substances.
As we all know, coal represents the fossilized remains of ancient plants and animals. And as every Sci-Fi fan knows, all the living inhabitants of this planet are “carbon-based life-forms.”
So, after the process of fossilization eliminates most of the other substances and materials, the carbon still remains very far away from its purest, diamond-grade form. Same goes for graphite and other common carbon-based materials.
So, unless you find a piece of 100% pure carbon, a magic spaceman won’t be able to turn it into a diamond for you, regardless of all the superpowers at hand.
- Does Coal Become Diamond?
- Are Black Diamonds Just Coal?
- What Is The Difference Between Diamonds And Coal?
How Diamonds Were First Formed?
Now that we’ve discussed the building blocks of diamonds, let’s see how they are turned into diamonds.
For that we will have to travel to Precambrian Eon – the period between Earth’s formation (let’s say 4,600 million years ago, give or take) and the start of the Cambrian period (the point where most of the major groups of animals started roaming the Earth about 541 million years ago).
That’s yet another piece of evidence that debunks the theory that diamonds are made from coal: Coal is mostly made from life forms that started their life journey during the Cambrian period.
If we are to be a bit more precise, we could say that most of the discovered diamonds – and diamonds in general – were formed somewhere between 3 billion years and 1 billion years ago under very specific conditions at the depth of 150 to 200 kilometers below the Earth’s surface.
The picture above illustrates how deep we need to go to find the original birthplace of diamonds.
If this looks a bit shallow we would like to point out that this is the point very early in Earth’s history, where the planet was still forming under some incredibly violent circumstances.
So, what exactly happened all that time ago?
Well, the large carbon deposits that were once forming the Earth’s crusts found themselves deep within the surface of the planet due to geological reasons we won’t cover in greater detail.
Be that as it may, the conditions so deep underneath the Earth’s surface were very rough back then (as they are today).
Namely, the carbon in question was exposed to the extreme temperatures of 1050 degrees Celsius (1200 degrees Fahrenheit) and even more extreme pressure of 725,000 pounds per square inch.
Just to illustrate, this is 50,000 times more than the atmospheric pressure at the Earth’s surface.
In such a hellish environment, the carbon was slowly pressed, molten, and crystalized into its purest form we know as diamonds.
So, you take the pure carbon, expose it to extreme pressure and heat and you get the diamonds. It’s not that different from what Superman did in his third cinematic outing – but the material he used was off.
How Diamonds Traveled to Earth’s Surface?
By now, we’ve solved the first piece of the puzzle. But, how did the diamonds become available to humans?
As a bit of trivia, diamonds were first discovered in the 4th millennia BC in India – people back then were not able to dig to the depths of 160 kilometers below the surface. So, the diamonds had to find a way to travel closer to the surface to become available to us.
Fortunately, they did – enter the Kimberlite pipes.
If you’re unfamiliar with the term, Kimberlite pipes got their name after the town of Kimberley in South Africa – the place where the famous diamond Star of South Africa was discovered back in 1869.
Kimberley is also home to one of the biggest open-pit mines in the world called the Big Hole which was formed as a consequence of a violent volcanic eruption a very long time ago.
That’s the point where things start to jell together.
So with that in mind, Kimberlite pipes, much like their South African cousin we talked about above, are believed to be formed by incredibly violent deep-source volcanic eruptions.
According to some sources, the last one of these eruptions occurred around 40 million years ago which was a very long time ago but firmly after the diamonds were formed below the Earth’s surface.
What happened essentially was that the Earth back then was way hotter, so the source of eruptions was more deeply rooted than the ones we see today. These massive explosions drilled cone-like tunnels through the inner layers of the Earth making a sort of highway to the surface.
As you can expect, in some cases the speeding magma traveling above picked up some of the diamond deposits and sprinkled them all over the surface.
The explosions were so violent that the diamonds needed only a couple of hours to travel to the upper layers of Earth at the speed of about 20 to 30 miles per hour. Not weeks, not days, but only a couple of hectic hours.
The image below illustrates how one of these explosions might have made the diamond available to our ancestors six thousand years ago:
Now, there are a couple of bits we would like to discuss on this occasion.
First, there are a lot of people rushing to the places of volcanic eruptions hoping they will find some untapped diamond deposits. For instance, Hawaii – a country formed by ancient volcanic eruptions – has become a sort of hotspot for ambitious diamond prospectors.
Unfortunately, not all volcanic eruptions were made the same, and Hawaii, to this date, hides no confirmed diamond deposits.
Diamonds are, in most cases – we will cover other origin stories in a bit – a very fortunate by-product of eruptions that formed the Kimberlite pipes.
As we already said, the last one of those occurred 40 million years ago and the new ones won’t ever happen again due to vastly different geological circumstances.
So, the diamonds we got all that time ago are the diamonds we will have to rely upon until we learn how to dig hundreds of kilometers below the surface.
Where can we find these all-important Kimberlite pipes, then?
Well, this is yet another factor making diamonds an incredibly rare commodity and thus blowing their market value through the roof – the Kimberlite pipes are a very rare commodity themselves.
As we already briefly touched upon, the first Kimberlite pipes were discovered in South Africa when they got the name and were long believed to exist only in this specific corner of the world.
Since then, they were discovered on virtually all other continents – but they’re hardly a common good.
These days, we can find large deposits of Kimberlite-bred diamonds in South Africa, Russia, Botswana, Angola, Canada, and Australia – but that’s pretty much it. The diamond deposits in India – the location that originally got the ball moving – are long since depleted.
To sum it all up – diamonds are a crystallized form of carbon that was brought to life under extreme pressure and heat we could find approximately 160 kilometers below the Earth’s surface some 3 billion years ago.
Fast forward a few billion years, and we have the formation of Kimberlite pipes – the violent deep-source explosions that sent molten magma rushing to the surface, picking up the already formed diamond deposits to the surface.
That’s why some of the biggest diamond mines in the world are located in the vicinity of these 40 million years old Kimberlite pipes.
What Are the Other Ways the Diamonds Are Formed?
So, this was the story about the formation of diamonds. The thing about them is that their origin story is pretty formulaic. In spite of all the ethereal aura they are painted with, to get diamonds you only need pure carbon, extreme temperature, and extreme pressure.
With that in mind, can these ingredients line up in some other circumstances other than the formation of our planet?
The short answer is – sure. As a matter of fact, scientists have by now discovered diamonds that were created in quite a few different ways. In this section, we’ll quickly cover these rarer diamond-forming instances.
Diamonds Formed in the Subduction Zones
In order to understand this type of formation, we will first need to quickly explain the geological process of subduction.
So, as you’ve probably heard, the Earth’s mantle is composed out of huge tectonic plates that have, over the course of an incredibly long geological period, been moving around and formed the continents we know today.
Obviously, these massive plates have a lot of converging points where they have an opportunity to hit against each other.
Although the motions they were making throughout history were very slow, they were, due to the force and sheer mass of the tectonic plates, very violent and explosive. These days, the instances of these tectonic interactions are often followed by massive earthquakes and even volcanic eruptions.
Also, for the sake of this conversation, it’s important to mention that, when two parts of the Earth’s mantle violently converge, the heavier plate dives beneath the other one in the geological process we call subduction.
The regions where this process occurs are therefore called subduction zones.
It’s also essential to mention that the process of subduction creates astonishing pressure and releases a very high amount of heat. As we know, both these ingredients can cause the formation of diamonds.
That’s the exact way how the subduction zone diamonds are eventually formed.
As the image above shows, the creation of subduction zones usually occurs in the case when oceanic and continental plates converge with each other. Since oceanic plates are far heavier, they are subducted underneath the continental mass.
So, subduction zone diamonds are usually discovered near the coastline area.
When the process of subduction is terminated, the diamonds are safely preserved deep underneath the Earth’s mantle and brought to the surface by obduction – or by traveling with suitable magmas.
Still, as amusing as this may sound, subduction zone diamonds are the most important for the geological theory of tectonic plates. In reality, they’re too small to hold any real commercial value, so they’re not often discussed outside the scientific community.
Diamonds Formed due to Meteorite Impact
So, we have by now covered two instances when nature produces sufficient heat and pressure to crystalize carbon into its purest diamond form. The third case may sound a bit too far-fetched, but it has been scientifically confirmed more than once.
Of course, we are talking about the various meteorite impacts that have forever scarred the surface of the Earth in the ancient geological ages.
One of the best examples can be found in northern Siberia (Russian Federation) where, about 36 million years ago, a massive asteroid, roughly 5 to 8 kilometers wide, hit the surface at the estimated speed of 20 kilometers (12 miles) per second.
It created a giant crater that now spreads across the diameter of 100 kilometers (60 miles). The image below illustrates the current location and the look of the crater.
We can say that such a violent impact more than qualifies to squash carbon into a crystal form. So much so that scientists claim that the reason why we can’t find diamond directly at the impact site is that heat and pressure were too high and diamond material simply evaporated.
But, the impact of the meteorite did instantly melt 1,750 cubic kilometers (420 cubic miles) of rock present on the ground at the moment, instantly transformed carbon-rich material into small diamond particles and spread them all across the adjacent area.
They were first discovered back in 1972 by a Russian science expedition, and ever since then, the meteorite impact diamonds have been firmly established in contemporary science.
Of course, Russia’s Popigai crater is not the only example of meteorites hitting the Earth’s surface so violently they turn the carbon deposits in the diamonds, although it is the most memorable – and most important – example.
The thing that connects all these deposits, however, is that they are drastically different from their distant Kimberlite pipe-born cousins.
Namely, meteorite impact diamonds we have discovered up until now were formed mostly out of the graphite deposits that were present in the vicinity of the surface. Because of that, they have a drastically different structure than traditional diamonds.
For instance, meteorite impact diamonds are incredibly tough – even tougher than Kimberlite diamonds – but they inherit their tabular shape from the baseline graphite material.
They mostly appear as small crystalline particles, pack some sort of hue (yellow, brown, or black), and offer some unique optical features, like high birefringence and an entirely straight extinction.
All these things mean they’re not very sought in the world of jewelry – but don’t diminish their industrial value. So, they are mostly used for these purposes.
Diamonds from Space
If the previous formation theory sounded a bit too Sci-Fi for you, wait until you hear this one.
So, even though various meteorites and asteroids eventually find their resting place on our beautiful planet, Earth is far from the only space object they make a collision with along the way.
As a matter of fact, these journeys can sometimes last for countless millennia and feature an uncountable number of collisions. As you can probably guess, every one of these space traffic accidents creates the perfect conditions for the transformation of carbon into diamonds.
The available materials are also very abundant – unlike life, carbon is more than well-spread across our universe.
Now, take into consideration the fact that Earth is hit by approximately 17 meteorites a day and the planet itself is a couple of billions of years old and you will get a good idea about the probability of these space diamonds eventually finding a way to our home-world.
And, if we take a look at an image below we can see that Earth and Mars are surrounded by a massive asteroid belt. So, the fresh income of new space objects won’t stop hitting the planets anytime soon.
So, the theoretical blocks are definitely in place – what about the scientific confirmation?
Well, in 1987, a team of scientists examined some primitive meteorites and found microscopic grains of diamonds trapped in them (approximately 2.5 nanometers in diameter).
Upon closer examination, the same team discovered that the isotopic signature of the noble gasses found in the diamonds indicates they originated far outside our Solar System. Some theories say they’re even older than its formation.
Although these diamonds are too tiny for any sort of practical or commercial use, they have a significant scientific value. And since they are fairly common, they represent a very popular form of romantic present.
But, this is not the end of the story about extraterrestrial diamonds.
Namely, the experimental research indicates that our Solar System neighbors Uranus and Neptune may also deposit tremendous quantities of diamonds under their respective surfaces.
But, that’s not all.
Back in 2004, scientists discovered the so-called “super-Earth” – a planet named 55 Cancri e. The interesting thing about this plant is that a large percent of its total mass is made primarily from carbon in its diamond and graphite forms.
That would make the 55 Cancri e the biggest diamond known to men, with a total mass of 10 billion trillion trillion carats.
Still, until we find a way to access these riches and harness them, these fun facts will remain only that – a couple of fun facts.
In one of the previous passages we have mentioned that, in this day and age, people have a pretty good understanding of how the diamonds are formed and what prerequisites need to be set in place to get this precious material.
Cutting to the bare essentials, those would be a lot of carbon, the temperature that sits between 2,000 to 2,200 degrees Fahrenheit, and the pressure of approximately 725,000 pounds per square inch.
If we were able to emulate these conditions, would we get diamonds as a result?
The answer is one big unanimous yes. Furthermore, artificial man-made diamonds have been hardly fresh news for half a century now.
The first synthetic diamond particles were produced in the early 1950s by researchers in Stockholm, Sweden, in the same exact way we have described above.
In the time since, the process for the production of diamonds has become more refined, faster, and industrialized. So, these days, you only need a couple of hours to do nature’s work and turn ordinary carbon into this precious material.
Of course, this doesn’t mean the process has become any cheaper – or that lab diamonds have disturbed the entire gemstone market. People like to own diamonds because of their rarity, so the natural stones still have their worth preserved.
But, we can’t forget that diamonds, due to their magnificent natural properties, also have a critical place in modern industry. Relying on scarce natural diamonds to satisfy these industrial needs would bring the whole business world to a grinding halt.
That’s why companies like Diamond Innovations, De Beers, Sumitomo Electric, and others work tirelessly to produce the annual amount of more than 100 tons of fresh diamonds that are later poured down in various industrial branches.
In most cases, these lab-grown diamonds are used for cutting asphalt and marble, like drill bits in the O&G industry, or even as an exfoliant in cosmetics products.
Learn More: What Are Diamonds Used For Other Than Jewelry?
So, how exactly is the carbon treated to get that shining facelift? In most cases, we would use one of the two following ways:
- HTHP method – The letters you have just read stand for High Temperature/High Pressure. As you can guess, this method uses a carbon-rich material (usually graphite very similar to the one you can find in an ordinary pen), and puts it into a machine that tries to recreate the natural conditions, treating material to extreme heat and pressure. Since the process requires the inclusion of metallic elements, the resulting diamonds are not as pure as the ones that are the result of natural processes.
- Vapor disposition – Contrary to the previous method, using vapor disposition gives birth to diamonds that are even more flawless than the ones you can find in nature. But, in order to get such results, you need a seed diamond (usually a fingernail-sized imperfect piece) that’s then put in the vacuum chamber, and relentlessly zapped with microwaves. The inclusion of gasses, like methane and hydrogen, in the process causes gas molecules to stick to the diamond, creating far superior and better-looking pieces.
Recently, a team of scientists from Australia discovered yet another way of manufacturing synthetic diamonds that relies almost exclusively on applying immense pressure on carbon atoms.
The said diamonds were formed at a regular room temperature and were 58% harder than their natural-born brethren.
That was a huge scientific breakthrough, and once this process becomes more refined and better suited to serialized production, the diamond manufacturing industry may experience the biggest revolution since the 1950s.
It feels good to know, though, that although the deposits of diamonds on Earth are ultimately finite, human ingenuity is anything but.
How People Discovered First Diamonds?
Keeping in mind that historians believe that the human race first came in touch with diamonds as early as the 4th century BC, tracing back the exact moment when this mineral was uncovered for the first time is near impossible.
If any records of these excavations ever existed, they’re now long lost in the winds of history.
What we can guess, however, with a large amount of certainty, is that these beautiful stones were first discovered on the Indian Subcontinent.
That’s a very fortunate fact, taking into consideration that India sits right at the middle of the so-called “Silk Road” – an ancient trade route spreading all the way from China to modern Turkey and Italy.
Because of that, the rumor spread very fast and India, with its seemingly limitless deposits of natural wealth, became a fabled land of fortune – but also a target for numerous foreign conquerors.
By the 15th century, the diamonds found their way to Western Europe, becoming the most popular gemstones of the European feudal elite. However, this tireless exploitation of natural resources couldn’t last forever.
By the end of the 18th century, Indian diamond deposits pretty much dried up.
This unfortunate turn of events gave birth to another massive stage of diamond prospecting since, with the exception of small deposits discovered in Brazil during the 1700s, diamonds were believed to exist almost exclusively in India.
Thus, the story of modern diamond mining starts on an entirely different continent – Africa – and the discovery of diamonds near the town of Kimberley we briefly touched upon earlier.
The honor of ushering this new diamond-clad era goes to a 15-year old farm-boy Erasmus Stephanus Jacobs who discovered the first diamond pebble near the Orange River, Hopetown.
This discovery was entirely serendipitous, while the stone was christened with an entirely appropriate name of Eureka. As you can guess, the discovery of Eureka caused countless numbers of diggers and prospectors to flush the region and try to forge their own destiny under the hot sun of South Africa.
It turns out that most of the fame and fortune will eventually end up in the hands of the ambitious 19-year old English citizen Cecil John Rhodes. He innovated the mining techniques, imported a couple of steam-operated pumps, and started the De Beers diamond empire around the deposits in the Kimberley mine.
The name, by the way, comes from Johannes De Beer on whose farmland the diamonds were originally discovered.
Related Read: The Diamond Industry: How Does Diamond Business Work?
How Diamonds Are Discovered Today?
So, from the previous passage, we saw that the modern era of diamond mining was basically started by a happy accident – a boy found a shiny stone and the snowball started rolling.
But, what happened after the word of South Africa’s wealth spread like wildfire? How were rich diamond deposits discovered since then and how were they mined?
Let us delve deeper into the mining lingo.
Up until now, we learned that diamonds are formed in the depths of Earth – 160 kilometers, more or less – and carried away with other rocks through the so-called Kimberlite pipes aka diameters.
As a reminder, these carrot-like bodies appear as a result of violent underground explosions that result in volcanic eruptions.
Once they travel to the surface, they become embedded in the primary rock emplaced in the crust. These supplies are called primary diamond deposits.
It’s also good to remind ourselves that not all Kimberlite pipes are encrusted with diamonds. In the case they are, some Kimberlite pipes contain more substantial amounts of diamonds than others.
Now, as time goes by, and surrounding rocks are worn out by weathering, the Kimberlite pipes erode, as well – often faster than the surrounding rocks – and diamonds become released from the kimberlite.
As for the material itself, it degrades into yellowish compound miners like to call “yellow ground.”
So, you can take this as one of the first giveaways of the diamond-rich areas.
What’s even better – at least for the ambitious diamond miners – the diamonds located in the yellow ground can be washed out into various streams and eventually end up in alluvial deposits.
And in some cases, they travel so far from their place of origin, they are washed off the land right into the sea, like in the case of Namibia.
So, although they mostly originate from Kimberlite pipes, the fast erosion of this material can bring diamonds virtually anywhere in the reasonable vicinity of the primary deposit.
So, how can diamond prospectors inspect the ground for the presence of diamonds?
A good place to start is to look for kimberlite.
That, in turn, can be achieved by a variety of techniques, the most important of which being sampling for indicator materials.
Namely, aside from diamonds, the eroding kimberlite pipes also contain a vast quantity of other minerals and materials that may point out the presence of these precious rocks in the ground.
Some of the most notable mentions are chromium-rich magnesium garnet, magnesium-rich ilmenite, chromite, and Cr-diopside. The presence of these materials can then be traced to the place of greater abundance, like, for instance, taking more samples upstream.
Once the Kimberlite pipe is finally found (and that can be much harder than it looks, taking into account their massive proportions), it must be tested for the presence of diamonds.
Even if they are present in the pipe, their concentration needs to be high enough to warrant very expensive commercial mining.
So, what sort of concentration is considered to be sufficient to allow commercial viability?
At this very moment, the mining industry consensus sits somewhere at 0.1 carats (0.02 grams) of quality diamonds per ton. Preferably, miners should try to get 0.5 carats per to make some real money.
If these numbers sound too low, they’re simply a reality of the mining industry. Diamonds are a very valuable – and very scarce – commodity, so it makes sense to take out a ton of earth to get only 0.02 grams of the material.
To illustrate this scarcity, the highest diamond concentration recorded in recent history was scored in the Argyle mine in Western Australia. At its peak, Argyle was able to pump out only 6 carats (1.2 grams) per metric ton.
How is Diamond Mining Performed?
Last but not least, we’ll briefly cover how diamond mining starts once a sufficient concentration of diamonds is discovered in kimberlite-rich soil.
Well, for these large quantities of diamonds to become available, large amounts of rocks and soil need to be moved out of the way. This process starts with giant steam shovels and giant trucks that are necessary to remove all that material.
As the miners go deeper below the surface, and the terrain becomes rockier, the process of mining becomes more mechanized.
In the early days of modern diamond mining, the miners would simply take out the blue ground, throw it into big piles, and wait out until the weathering turns the kimberlite into the yellow ground.
These days, things move at a far more different pace.
Once the kimberlite is extracted, huge quantities of rocks are mechanically crushed, and then diamonds and other materials are gathered up by the machines.
The materials are first separated by their specific gravity, while finer stages of separation use more selective means, like grease tables and X-ray scanning.
In the case of alluvial diamonds, things are a bit simpler. The ground can be dug out by a simple shovel, but the process still involves moving large quantities of rock and long separation – this time from gravel – that’s usually performed with running water.
That is one of the rare instances where diamond mining still falls under the wing of artisanship and can be performed by human labor.
Still, at the end of the 19th century, this was the only way to get diamonds out of the Kimberlite pipes.
Every carat that came to the market was paid with sweat, countless hours of hard labor, and sheer determination.
Related Read: Which Region Specializes in Diamonds?
We hope you enjoyed this short journey spanning from the very creation of diamonds to the point where they became available to humans – and finally got into industrial production at the end of the 19th century.
Diamonds are considered to be one of the most valuable commodities on the planet. Their formation, scarcity – and immeasurable effort that goes into mining – partially explain their staggering value.
But, all good things come in small doses, and nature made sure to make diamonds just challenging enough to capture the hearts and souls of humanity.