This still doesn’t answer the question, because we still need to transport diamond from the high-pressure niche where it grew to the very low-pressure environment of Earth’s surface so we can mine it and make pretty things or super hard industrial tools. An enigmatic type of volcanic eruption called kimberlite (named after Kimberley in South Africa where they were discovered) achieves this feat, because they are thought to erupt at super-sonic speed through more than 150 km of the Earth and transport anything in their path to the surface, including diamond. So the hunt becomes easier; now we just need to look for kimberlites on cratons right? Wrong. Diamond is super hard, which means rivers can transport it for hundreds of kilometers without damaging it. This is why movies like Blood Diamond show people sieving diamonds from rivers – but we’ll come to blood diamonds a little later. In fact, in my opinion, the most bizarre diamond mine is located off the Namibian coast in the Atlantic. Here diamonds are sucked up from beneath the waves using massive machines that look like the offspring of vacuum cleaners and oilrigs.

Dirty diamonds vs clean diamonds

Now let me explain why I like dirty diamonds and jewellers like clean diamonds. Gemologists classify diamond using the 4-C’s, a classification protocol established by the Gemological Institute of America (an independent non-profit organisation). The 4-C’s are the [1] Cut, [2] Clarity, [3] Colour, and [4] Carat (where 1 carat = 0.2 gram, but was actually developed using the weight of Carob seeds). Conversely, geologists like me apply the 4-W’s, a classification protocol I made up for a lecture I gave to Gemology students at Kingston University. The 4-W’s are [1] What is this? [2] Where did this come from? [3] When did this form, [4] Why did this happen?

To answer my four questions requires a bit more than pure diamond, because pure diamond is usually comprised of 99.9% carbon and 0.1% nitrogen. Note, add more nitrogen and the diamonds turn yellow, remove the nitrogen and add boron and they turn blue, irradiate diamond and it turns green, and deform diamond to turn it pink/brown.

The real age of a diamond

Carbon and nitrogen are useless for deciphering the age of a diamond, and are only mildly useful at illuminating the chemistry of the environment where they formed. This is why geologists look for dirty spots, or 'inclusions' as they are more commonly termed. These dirty spots are sometimes minerals from the deep Earth, and by looking at their chemistry we can peer into the deep Earth (note, the deepest samples of the Earth ever seen are diamond inclusions.) We can also use radioactive isotopes to determine an age for the inclusion (and then assume that it is the same age as the diamond). By doing this it appears that most natural diamonds are seriously old, I’m talking 3.6-0.9 billion years old! We also know that some of the largest diamonds formed from carbon that used to be in the oceans and was recycled back into Earth’s interior by the processes of plate tectonics – in fact, some of the carbon in these diamonds may have once been ocean dwelling creatures. Another fun fact, at present we don’t really know if gem-quality diamonds are still forming today, so gem-quality diamonds could well be a finite commodity.

Now, if that didn’t impress you, this fact surely will. The oldest pieces of anything we have ever seen are diamonds formed in solar systems that no longer exist. In short, they formed planets that maybe hosted life, they existed for billions of years and then succumb to their inevitable fate – they were destroyed when their central stars exploded (called a super nova) – and this all happened before our solar system existed. That’s right, some diamonds are older than our whole solar system. In fact, if the solar systems that existed before ours were hosts to a planet like Earth with life like us writing articles like this, then all that may be left of them are what scientists who study meteorites (meteoriticists) call pre-solar grains: tiny diamonds around 1 micrometer in size (0.001mm). I don’t know about you, but this concept blows my mind.

Blood Diamonds

Anyhow, an article about diamond wouldn’t be complete without some words on Blood Diamonds, and synthetic diamonds.