A massive 1,174-carat diamond was recently recovered from the Karoy mine in Botswana, making it one of the largest natural diamonds ever recovered.
More importantly, the stone was found along with many other similar diamonds weighing ت 471, 218 and 159 carats – indicating that the original diamond could have weighed more than 2,000 carats when it was first formed.
The latest discovery came on the heels of another massive diamond weighing more than 1,000 carats that was recovered from the Guaneng Mine, also in Botswana, just a few weeks ago.
Why are we witnessing a sudden rush to recover these giant gems?
Are diamonds really “rare”?
In 2020, global diamond production reached 111 million carats or just over 20 tons of diamonds. However, a small percentage of this production is of high quality gemstones. The vast majority of diamonds are small, less than one carat.
Australia’s Argyle mine, famous for its pink diamonds (and once the world’s largest diamond mine by volume), ceased operations late last year because it was no longer economically viable. This is because most of the diamonds mined were small, and therefore only useful for industrial applications.
These small diamonds are so common that a diamond-tipped writer’s tool can be purchased for less than the price of a tank.
On the other hand, large gem-quality diamonds are extremely rare. To understand why, we need to look at how diamonds are formed, as well as how they are extracted.
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How are natural diamonds formed?
Natural diamonds are billions of years old. They formed deep in the Earth where temperatures and pressures are high enough to crush carbon atoms into a dense crystal structure.
Some scientists have suggested the existence of huge amounts of diamonds hundreds of kilometers deep. But since the deepest hole ever drilled is about 12 kilometers long, we’ll never be able to extract these diamonds deep underground.
So we have to deal with the relatively small fraction that comes to the surface. Diamonds near the Earth’s surface are usually thought to have been interrupted by a deep-source volcanic eruption.
These violent events must be fast enough to bring the diamond to the surface, and at the same time, the diamond cannot be exposed to extreme heat, shock, or oxygen. It’s a tight Goldilocks scenario.
Most diamonds are found within an igneous rock called kimberlite. Kimberlite “tubes” are island-shaped rock pillars, often only tens of meters wide, at the top of deep source volcanoes.
But only a small percentage of all known kimberlite deposits contain diamonds. And only a handful of these are rich enough in diamonds to warrant mining.
It is very difficult to find ideal conditions. Only certain regions of the continent can host diamonds as the crust must be thick enough to host a deep volcanic event. It must also be stable and old – characteristics common in parts of Australia and Africa.
Furthermore, despite its reputation as indestructible, diamond is a brittle material. This property must be taken into account when polishing diamonds and turning them into gemstones. At normal atmospheric pressures, diamond is not even the most stable arrangement of carbon atoms.
Large natural diamonds that manage to survive the winding path to the surface are often destroyed by the same process of finding them. In most diamond mines, the ore is blasted with explosives and then crushed into shrapnel to search for diamonds.
But new technologies allow mines to process ores with the help of X-ray ore sorting technology. This is specifically targeted at “mega diamond recovery”.
Although the diamond world is known for secrecy regarding details, we do know that the most recent diamonds from the Karowe Mine have been recovered using these newer technologies. It is likely that more of these huge stones will be discovered in the future.
Advances in diamond mining techniques, along with the inherent scarcity of massive diamonds, are a boon to Botswana, with diamonds making up a large part of the country’s GDP.
diamonds in the lab
Diamonds get bigger in the lab, too. For decades, synthetic diamonds have been manufactured using high pressure equipment that simulates the harsh physical conditions deep in the earth.
Now, new technology that uses low pressure conditions and carefully controlled chemistry can make perfect dinner plate-sized diamond discs.
This chemical approach is used commercially to manufacture gem-quality stones for jewelry. But making diamonds this way requires patience. It takes the best part of a day to grow a millimeter of diamonds, which means that mining will likely play a major role in the diamond industry for some time.
READ MORE: More Than Just A Sparkling Gem: What You Didn’t Know About Diamonds