One of Mother Nature’s purest and rarest occurrences.
Diamonds have fascinated us for centuries, but what miracle of nature, deep within the core of the earth, can cause a vulgar carbon molecule to turn into a structure as pure and perfect ?
Let’s begin this journey in space and time…
Birth of a Diamond
Diamonds are believed to have formed between 1 and 3 billion years ago, in the depths of our planet and under absolutely exceptional conditions!
While geologists tend to have diverging opinions on the exact intricacies, all seem to agree on the general process:
- Bury carbon at a depth of 90 ~ 120mi.
- Raise temperature to 900 ~ 1,300 °C
- Pressurize carbon to 45~60KBars
- Thrust carbon up to earth’s surface
A bit of explaining is in order…
At such depths, the high temperature causes the carbon to be found in its liquid state only. As it undergoes incredibly high pressures, the liquid carbon crystallizes.
The carbon crystals – or diamonds – enclosed in a Kimberlite envelope, were then thrust up the earth’s surface during volcanic eruptions, riding the magma flow through the cracks in the earth’s crust.
Formation of a kimberlite pipe.
Tens of millions of years later, once the volcano is extinct and eroded, diamonds can expectedly be found in old magmatic columns full of Kimberlite (also called “Kimberlite pipes”).
The location of a kimberlite pipe thus defines the location of a primary deposit.
Rough diamond enclosed in a kimberlite rock.
But don’t be fooled by it: chances of finding a commercially viable pipe are only 1 in 200!
Diamonds can also be found in secondary deposits, when the diamonds are eroded from the host rock into alluvial deposits (rivers) or marine deposits (beaches), scattered over distances of several tens of miles.
Rough diamonds in alluvial deposits.
Operating of a secondary deposit can be downright rudimentary when diamonds are present on the shores of shallow waters, or more industrial if a dam or a pump has to be built to extract diamonds buried in the sand at the bottom of the oceans.
The first diamond discoveries can be traced back to the ~800BC around the city of Golconda, India.
For 2,500 years, until 1725 , India was the only producer of diamonds in the world and Golconda its almost sole source, exclusively from alluvial deposits!
The ancient mine of Golconda Fort, India.
During the Middle Ages, rough diamonds were chartered to Europe by boat through Venice , Lisbon and London …As a result, the first guild of diamond polishers and cutters was formed in 1375 in Nuremberg, Germany.
14th century Italian merchants.
However , it is in the city of Antwerp , Belgium – one of Europe’s largest trading ports at the time – that the diamond market developed most quickly. The artisans of the city had acquired a growing reputation of being the most skilled workers in their field.
Logically, it was in Antwerp that the first official diamond guild, the Diamantsnijdernatie, was created in 1582 .
Engraving of diamond polishers in the 1500s, in Antwerp (ca. 1720).
Diamond extraction only began in the 1870s after the discovery of the diamond fields, in South Africa.
Despite the industrialization of the mining processes, the occurrence of finding diamonds still remains almost miraculous; it is sometimes necessary to treat 250 tons of rubble to retrieve one carat of diamonds!
Furthermore, out of the 100 million tons of diamonds mined each year, only 20% are gem quality.
The gigantic open-air Mir diamond mine, in Russia (closed since 2004).
Diamonds From Outer Space
In the late 1800s, traces of diamonds were discovered on meteorites fallen on the earth some 50,000 years ago…
However nothing comes close to the discovery made in 2004 by the Harvard-Smithsonian Center for Astrophysics, who unveiled the existence of a gigantic mass of crystallized carbon – by far the biggest diamond in the galaxy.
The so-called BPM 37093 extends over 4,500km and weighs a whopping 10,000,000,000,000,000,000,000,000,000,000,000 carats!