Everything You Need to Know: Diamond Mining

Marilyn Monroe said they were a girl’s best friend. James Bond fans say they are forever. Of course we’re talking about diamonds. The brilliant gemstones that give you cut, colour, and clarity in spades.

Whether it’s for the tip of a sawblade or the centrepiece of a dazzling ring, diamonds, with their natural rarity, glamour, and hardness, have driven us as a species to extreme lengths just to get them out of the ground.

But what does it take, to get a diamond out of the earth and onto your finger? What are the swathe of complex processes it takes to turn “just some shiny rock” into an iced out disco ball on your wrist?

And what is this sparkly industry’s dark secret lurking just below the surface?

A story a billion years in the making. This is everything you need to know about diamond mining. Time to bring the bling.

Digging Deep – Where do Diamonds Come From?

So, where do diamonds actually come from? Most of us know that they’re formed out of carbon, but how does a diamond actually begin its life before it ends up on the finger of your beloved? Well, a diamond’s life begins hundreds of miles under the earth’s surface up to a billion years ago. There, miles under the earth, crushed by everything around it, the pressure is 45,000 times stronger than it is at sea level.

At that pressure, atoms of carbon slowly crystallise into what we know today as diamonds. And this makes sense, as we know that diamonds are considered the hardest naturally occurring material on earth, they would have to be hard to survive all of that pressure.

And that deep in the earth, it is hot, molten even. A kind of coarse igneous rock called kimberlite is where those diamonds formed primarily, although they can be found in other kinds of rock as well. But how do diamonds reach the surface?

From time to time, over hundreds of millions of years, the pressure would be so intense that when tectonic plates began to shift, the molten kimberlite would force its way upwards in an eruption, at up to 30 kilometres an hour through the earth’s crust. These volcanic events would cause an eruption of kimberlite, bringing diamonds to the surface, and the molten kimberlite forcing its way through the earth’s crust would cool significantly and harden into what are known as “pipes” of kimberlite. And so that’s where diamonds are often found, either buried shallow in the earth from the eruption, or deeper underground, still in their kimberlite pipes that formed hundreds of millions of years ago.

The last diamond-bearing eruption on earth is believed to have happened over 100 million years ago, so if you, or someone you know own any diamonds (and you probably do), it may well be the oldest thing you own. But these eruptions weren’t very common, and so today the number of diamonds that have reached the surface are pretty rare, which along with their hardness and general beauty, is what make them an expensive commodity. In fact, all the gem-quality diamonds ever mined would fit inside of one London double-decker bus.

So, diamonds can be found in many parts of the world, but only in a small number of places are they found in great quantities, those being Russia (mainly Siberia), sub-Saharan Africa, Canada and Australia. Russia by itself mined close to 42 million carats in 2022. But as we said, diamonds are rare, so diamond mining companies can’t just be set up anywhere. Before a single spade can hit the dirt, companies employ the help of geologists to explore for kimberlites. As where there are kimberlites, there’s diamonds.

They utilise satellites, geophysics, and sampling to gather information about the landscape, and any kimberlites discovered can then be drilled into to establish whether they contain economic quantities of diamonds. Basically, they need to know if there will be enough diamonds in the rock for it to be worth it to mine, as mining operations can be very expensive due to the power, man hours, and equipment needed.

More so than that however, analysing a kimberlite core will give a diamond mining company an indication of the grade of diamonds they’ll get, the cost per tonne and the average value per carat, all of these factors will determine whether the “okay” is given and ground can be broken on a new site.

But then you actually have to get the diamonds from the ground to the jeweller’s shop. Which is an incredibly convoluted and labour-intensive process every step of the way. So, how is it done?

Ore Inspiring – How Does Diamond Mining Work?

In general, there are four kinds of diamond mining operations ongoing at any one time on our planet. The first two are the most basic, pit mining and underground mining; sometimes known as primary source mining or pipe mining. Because we know that diamonds come from kimberlite pipes that were brought up close to the surface millions of years ago, if you go where the kimberlite is, that being underground, you will find the diamonds.

Open pit mining is the most common and easiest mining operation to organise. It requires digging enormous pits dozens of metres into the earth. This is often done by removing the top layer of earth and rock with equipment and blasting the rest with explosives, because blasting at the right depth loosens the diamond-bearing rock and ore.

At this point, enormous earth-moving machines, combined with the back-breaking labour of individuals, mine out the ore and loads it onto absolutely enormous 300-tonne mining trucks that take it to the diamond processing plant. Most open pit diamond mines are in highly remote locations and they can be ruthlessly efficient, but are also expensive to operate, as all the workers need to be flown in, housed, and fed for the duration of the mine’s operation. So, diamond mine locations need to be selected carefully for the mining companies to financially sustain the process.

The other half of this operation is underground mining, which is a lot like pit mining, but deeper and totally underground. Sometimes open pit mines, if they’re profitable enough, will develop into underground mines as time goes on. Miners will tunnel to where they can find kimberlite pipes.

In fact, they actually use two tunnels, one underneath the other, separated by a 25-metre gap and funnel shafts running vertically between them. The idea is that miners dig out the kimberlite pipes in the upper tunnel, which then falls through the funnels to the lower tunnel, which is then collected and transported out of the mine for processing. This is known as block carving and has been used for decades as an efficient and relatively safe mechanised mining method.

It also helps collect other minable materials like precious metals which boosts profit. Of course, the downside is that this is even more expensive and still risky, but if you pick the right area, profitability is near guaranteed. But it takes a lot of work pipe mining requires moving 250 tonnes of earth to mine a single carat.

They are rare after all.

Following pipe mining, the next method is known as “Alluvial” diamond mining, and is what’s referred to as “secondary” mining. This doesn’t require miners to go directly to the kimberlite pipes themselves for diamonds, but instead focuses on sediment deposits in riverbeds and on beaches. Thousands of years of erosion from natural forces like wind, rain, and the current, wash diamonds from their primary kimberlite deposits into rivers and onto beaches, where it is often collected in the gravel layer.

Alluvial mining seeks to extract that gravel for processing. This could be as easy as an individual person panning for diamonds with a sluice or a bowl, much like old gold prospectors would. Or it can turn into a large industrial operation including building dams to trap the water and gravel, which can then be extracted with machines and processed.

It can even be used to divert rivers entirely, which then exposes the dried-up gravel layer where diamonds can be extracted from.

This is a particularly profitable operation if the right location can be found, as the water washing the diamonds downstream causes them to impact rocks on the way, breaking the diamonds that have structural flaws. As a result, most alluvial diamonds found are comparatively smaller than in pipe mining, but are often of higher quality and value. This does require picking the right area though, so a lot of preparation is needed beforehand before the money can roll in.

The final option is marine diamond mining, which seeks to extract diamonds from the ocean floor using specialised mining ships. This also is an indirect form of gathering diamonds and is split into two distinct categories. Horizontal marine diamond mining uses what’s known as a “crawler”, a large tracked piece of equipment that is attached to a surface vessel and dredges the seabed to gather the diamonds via a giant pipe that sucks sediment to the surface, from which the diamonds are then deposited and processed.

Vertical diamond marine mining uses a large ship-mounted drill which works in overlapping circles on the sea floor instead, the rest of the process is the same. Of course, the biggest barrier to entry here is capital, specific ships designed for trawling and the equipment used to mine the diamonds are highly specialised and so are often reserved for the companies that can afford this kind of equipment. Sometimes digging a big pit is just easier.

But if you can, it’s highly lucrative as many areas of the seabed are untapped.

From Tunnel to Tiffanys – How are Diamonds Processed?

And so, once the diamonds are actually mined out of the ground and reach the processing facility, how are they processed? How do we go from chunks of ore and piles of gravel to the brilliant, dazzling, well-cut diamonds we see adorning jewellery stores today?

So firstly, the larger rock is crushed via machines into smaller, more manageable pieces. Sometimes, a secondary crusher, known as a roll-crusher (think of those industrial shredders) are used to reduce the size of the ore and gravel even further. At the end of this process all of your ore and gravel is roughly the same size.

By then putting it through a washing process, where the diamonds ore is scrubbed to remove as much loose excess material as possible. At this point anything smaller than one and a half millimetres in diameter is discarded by the machine, which looks something like a large horizontal rotating drum. This is because it would cost more to extract the small pieces of ore from pieces than you would get back from selling them, although some companies do sort them into a “fines” section for other uses.

More scrubbing processes are used as well like log washers, high-pressure washers and attrition cells.

So, now you’re left mostly with pure diamond ore, but along the way other metals or even other gems will have made it this far in the cleaning process and still needs to be separated. To separate them, the diamond-bearing ore is then mixed with a water solution of iron and silicon powder known as ferrosilicon. This is a heavy liquid, and when you add this to the mix, the denser diamonds sink to the bottom, whilst other less dense materials float to the top. When this goes into a cyclone or a sluice with several panels and meshes, it’s a lot like panning, the heavier material stays whilst the lighter stuff is carried away.

Then finally the diamonds are sorted from the remaining heavy material. A relatively low-tech method for this is simply to use a greased belt which takes advantage of diamond’s hydrophobic qualities. Diamonds stick to greasy surfaces where other materials that have absorbed water will slide off, then you just have to scrape them off.

However, this isn’t a perfect solution, on a fully automated scale, magnets are often used to remove metals, whilst x-ray luminescence and lasers are used to separate the diamonds from any other dense materials that aren’t magnetic. Sensors are used to detect the flashes of light emitted by diamonds, this sends a signal to a microprocessor that fires a blast of condensed air at the diamond on the belt, which then spits it into a collection box. And if you can follow those simple 18,000 steps, you too can have a box of diamonds.

It really is that simple.

But actually, it’s not quite the end of the road. The diamonds collected in this recovery process then need to be cleaned in an acid solution, washed, weighed, sorted, and packaged in sealed containers for transport. The diamonds are often sorted by carat weight, and then each size is sorted into their quality ranges. Not all diamonds are created equal after all. This is also the point that the gemstone-quality diamonds are separated from the industrial diamonds.

Industrial diamonds are regarded as something of a byproduct in the diamond mining process. They certainly do have their uses, the lowest quality ones are still diamonds, as the hardest naturally occurring material on earth, they can still be used in various high abrasion sandpapers as well as on the tips of drill bits and saws. The reality is you just don’t make as much money from industrial diamonds as you do from the prettier ones.

And there are a lot of them, 80% of mined diamonds are considered unsuitable for use as gemstones for one reason or another. So, they too are sorted, and then the gemstone quality ones are placed in a box with an anti-tamper resistant seal, numbered on sight and issued with a certificate of origin.

From there, they’re viewed and sold by a confidential electronic auctioning process, usually to a licensed diamond trader. The highest bidder wins the parcel of diamonds and from there, some stay in their country of origin to be cut into gemstones, to ensure that the nation the diamonds are from is actually getting a cut of their own profits. Others are sold to jewellers and other diamond cutting specialists throughout the world where they’re moulded, polished, and set into that engagement ring your partner simply has to have.

But all that glitters is not gold… or in this case, diamonds. The diamond industry has a dark past, and a dangerous present that can’t be separated from the jewellery we wear every day. But it also has a hopeful future that hopes to one day leave that all behind.

All That Glitters? Controversy and Future

Diamonds have commonly been a vector for colonial empires to exploit other parts of the world throughout history. When diamonds were discovered in what was German Southwest Africa (the nation now known as Namibia) at the turn of the 20th centuries, it led to untold amounts of atrocities, violence and brutality. The German treatment of the indigenous Herero people is only just starting to be recognised as one of the earliest attempted genocides in recorded history, all in the name of colonial greed, and that included the mass plundering of diamonds found there.

British companies seized control of the diamond trade in 1930s Sierra Leone and for a long time none of that wealth was shared with the country’s people. There have been many such cases all over the world across history, including in India, but much of the exploitation for diamonds occurred on the African continent.

And worse yet, after those nations gained their independence, armed militias started to take control over diamond mines locally, they would use the proceeds from these highly profitable industries to further fuel their bloodshed and expand their operations. These are what are referred to as “blood diamonds” and the international community has been trying to eliminate them for over a generation.

Now remember in the diamond separation process where we mentioned that rough diamonds are placed in sealed containers, numbered and issued a certificate? Well, this is in accordance with something called the Kimberley process.

This was a process that was adopted when southern African diamond producing states met in Kimberley in 2000 to discuss ways to stop the trade in blood diamonds and ensure that diamond purchases were not financing violence. This, plus UN cooperation, resulted in the Kimberley Process Certification Scheme (or KPCS for short). The KPCS sets out the requirements for controlling rough diamond production and trade, and it came into force in 2003.

It requires diamonds to be certified as “conflict free” to stop any blood diamonds from entering the supply chain. And it worked. Before the KCPS was introduced, it was estimated that 4% of the world’s diamond supply were sourced from conflict, today that figure is estimated to be just 0.2%.

This is why you now get a certificate when you buy a diamond that tells you where exactly that it came from, and you can trace it all the way back to where it was mined.

However, that doesn’t mean everything is suddenly all good. Modern diamond mining operations are expensive, which means that unsavoury characters are always looking for a way to make their production costs cheaper so they can pocket more profit. But this leads to unsanitary, unsafe working conditions, and it also utilises indentured servitude, and sometimes child labour as well.

Diamond pits, or really any mining operation, especially in Africa, can be highly dangerous places. Heavy machinery, minimum safety equipment, poor conditions, risk of cave-ins, and more, are all just par for the course. Organisations have discovered overcrowding of workers, abuse, long hours, and cheap or no pay.

Child labourers in diamond mines suffer from a myriad of health problems, from their poor working conditions including eye strain, headaches, malnutrition, and respiratory problems. Many of them don’t have a choice. When you are dirt poor, and your family relies on your work to survive, what other option is there?

Human Rights Watch found in 2018 that the diamond mining industry still fuels this kind of suffering. The reality is some of the largest diamond companies in the world are at least complicit in it. They might not be blood diamonds but that doesn’t mean the industry is clean.

But before you tear your engagement ring off your finger, it’s not all bad, diamond mining clearly has a long way to go but these problems are slowly being addressed. The poor conditions of some mines are not the case everywhere, and in other places the Kimberley process is doing its job to ensure that diamonds can be sourced from pit to pendant. Meanwhile the diamond trade is also helping some former colonial nations rise out of poverty.

Botswana’s diamond operations have given the nation a significant economic boost. Diamonds are 71% of their export revenue and make up 16% of the GDP. The nation even has a stake in several global diamond traders to ensure that profits from diamonds all over the world, many of which it supplies, benefits the nation in return.

And if you’re not convinced that diamonds can be mined ethically, soon, it could be the case that diamonds mined from the earth will be a thing of the past. Every year the lab-grown diamond industry grows even larger. Under laboratory conditions, the conditions to manufacture perfect, dazzling diamonds can be replicated, and they’re also cheaper, costing on average between 60-85% less than their mined counterparts.

They are otherwise totally identical, and as the industry grows, regular diamond mining might become less profitable over time. The one downside is that it is actually worse for the environment, as unlike many mining operations, diamond mining ironically has a very low carbon footprint because it doesn’t use any chemicals. According to the Diamond Producers Association, the emissions of a one-carat, polished, natural diamond are less than that of most synthetic diamonds of a similar size.

So, it seems diamond mining might be in for a shake up in the future, perhaps one day, this industry and the incredibly complicated series of steps it takes to orchestrate, hundreds of millions of years in the making, will be just as extinct as the dinosaurs that were around when they were first formed. Or perhaps the industry is simply too profitable to ever end, including the suffering it causes.

At the end of the day, diamonds are forever, and for the effort it takes to actually get them out of the ground, they probably should be.

Key Takeaways

• Diamonds form deep underground under extreme pressure and heat, then reach the surface through volcanic eruptions.
• Diamond mining involves four main methods: open pit, underground, alluvial, and marine mining, each with unique challenges.
• The Kimberley Process aims to prevent conflict diamonds, but issues like unsafe working conditions and child labor persist.
• Only 20% of mined diamonds are suitable for jewelry, with the rest used industrially due to their hardness.
• Lab-grown diamonds are becoming more popular, offering a cheaper and potentially more ethical alternative to mined diamonds.

Sources

• Original MegaProjects video: Everything You Need to Know: Diamond Mining
• Hero image source by Shemadeitagain / openverse, by-sa.

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