Digging deep: A look at how diamonds are formed

Buying and owning diamonds is one of the most unparalleled experiences in the world. There are very few people who can resist the beauty of a diamond, thanks to its brilliance and shine. They are the symbol of love and relationships that we are a part of every day, adding a special sparkle to life’s real moments.
What is it about diamonds, though, that makes them so precious and valuable? To be able to answer this question, however, let’s take a look at how diamonds are formed.  


Origins of a diamond

The word ‘diamond’ comes from the Greek word ‘adamas’ that means indestructible or invincible. A diamond is the hardest natural substance known to man, and that makes it very difficult to break or crush. And they are precious because they take almost a billion years to form. You read that right. The diamond you might be wearing at the moment is probably over a billion years old! While there are a lot of scientific processes coming together to make a diamond, one thing is for certain: they are nothing short of nature’s miracle.
Additionally, diamonds are a lot like humans in that no two diamonds are ever the same. Their uniqueness is what gives the wearer the wonderful feeling of being extraordinary and special. It is hard for most people to resist the beauty and charm of a diamond. 


How diamonds are formed?

Science says that there are four possible processes in which diamonds are formed – in the earth’s mantle, at impact sites, in a subduction zone or even in space! However, only one of these processes is common to most of the diamonds mined in the world – in the earth’s mantle.
It is amazing how the world’s most coveted gemstone is made under the surface of the earth, in a layer that is approximately 105 to 150 KMs deep. This layer, known as the mantle, has extremely high temperatures – approximately 2000 °F (or 1903.33 °C) – and intensely high pressures exceeding at about 7,25,000 pounds/square inch. All the heat and pressure cause the graphite’s atomic structure itself to transform; it changes from its hexagonal pattern to a more triangular one.

A typical diamond mine
A typical diamond mine.


It might just seem like this process takes months, at best, but that would be so far from the truth! It takes billions and billions of years for diamonds to form, and that too is possible only if all the conditions are favourable. After all, diamonds aren’t found everywhere below the surface of the earth. The most common places where diamonds are found, today, are Brazil, Canada, Australia, Russia, Borneo and several African countries such as South Africa and Botswana.
However, once the diamond deposits are made, the next logical question is: how do they come up to the surface or the ‘mines’ as we know them?

Kimberlite pipes: Nature’s brilliant diamond ‘transportation’ system

Nature has a fascinating and brilliant system to transport these diamonds to the surface, in order to make them accessible. The intense pressure and temperatures cause volcanoes deep inside the surface of the earth, leading to eruptions at the surface. The diamonds formed in the mantle, too, come up to the surface via the magma in what are known as kimberlite pipes and some of them end up in streams and coastlines’ sedimentary deposits. The kimberlite got its name from Kimberley in South Africa, the location where these pipes were first discovered.
Kimberlite pipes leave a bowl-shaped mark on the surface, making it easier for diamond miners to find a possible site to mine diamonds. However, experts say that only 1% of kimberlite pipes contain diamonds that can be mined for jewellery. The last kimberlite pipe eruptions happened over 40 million years ago when the earth was a much hotter place.

A diamond nestled in kimberlite
A diamond nestled in kimberlite


Sometimes, miners can also source diamonds from alluvial diamond sites. These are simply river beds and contain diamonds that came from kimberlite pipes and found a new home due to geological movement. In fact, it is very common for rivers, ocean or glaciers to transport diamonds thousands of kilometres away from where they were first reached the surface of the earth.
Diamond miners search for these diamond deposits, an extremely challenging task in itself. Sometimes, this search can take up to 10 long years. And even then, finding kimberlite deposits isn’t enough; it can take up to 10 more years to figure out if there are enough diamonds for the entire process to be economically viable. Only 15% of the diamonds mined across the world can be cut and used for adornment purposes. In fact, it is commonplace for miners to go through one ton of ore to produce just one carat of diamonds.
The diamonds that can be used, however, are then polished and processed before being available for consumers – either in the form of loose diamonds or to be made into jewellery.

What’s next?

Anyone knowing how diamonds are mined is wont to wonder what the next step is in the entire process. Where do the diamonds go before they end up with you?
The rough diamonds are cut and then anonymously sent to a gemological institute. Here, experts look at them under 10x magnification in order to determine their value. They use the 4Cs of
diamond evaluation – cut, colour, clarity and carat – to attach a value to each diamond. How much you pay for your diamond depends completely on this certification, hence, it is important to ensure that your diamonds’ certificate comes from a reputed laboratory. A small grade difference may not seem like much at the time of purchase, but it could mean you spending thousands of more rupees. Also, ensure that the jeweller you buy your diamonds from is trusted and reputed.


Understanding how diamonds are formed makes the already valuable diamond even more special. Whether you are gifting a diamond to your loved one or celebrating a personal milestone, you are buying a piece of history that is billions of years old. This is exactly what makes the diamond such a precious gemstone – it’s fascinating history, its brilliance, sparkle and shine, make it one of the most valuable possession you will ever own.