Ask the expert puts the questions people ask most about natural diamonds to the specialists who know them best. Each edition takes one question and gives it a clear, informed answer, straight from the source.
This time, it’s a big one: how rare are natural diamonds, really? It’s a question that keeps coming back, partly because the answer is so hard to picture. Natural diamonds form deep underground, over timescales that are difficult to grasp, and reach the surface only under very particular conditions.
Few people tell that story better than someone who has spent her career explaining it. Here it is, in her words.
Meet our expert, Beth West
Beth West is a gemologist and senior technical educator at De Beers, with more than 18 years’ experience in the jewelry industry. She is a Fellow and Diamond Fellow of the Gemmological Association of Great Britain and a member of the Federation of European Education in Gemmology, and her expertise spans advanced gemological testing and grading. Education is her passion, and she has made it her mission to share knowledge of natural diamonds across the supply chain. She has also volunteered with Diamonds for Peace and FairLuxury.
Diamonds are, quite simply, extraordinary
Let’s think about what a diamond actually is. It’s a crystalline form of pure carbon, tetrahedrally bonded in the cubic system. OK, that might sound dry but, fundamentally, it means the bonds between those carbon atoms are very short, very strong and very equal, which is what gives it its extraordinary properties: its unsurpassed hardness, its luster, its transparency. And, yes, synthetic laboratory-grown diamonds are structured in exactly the same way, but it’s how Mother Nature got those carbon atoms to exist in the structure, which is what makes it remarkable. No scrap that; it’s miraculous.
The formation of diamonds: a true moment of serendipity
Carbon was forged in the heart of stars in the earliest phases of our universe. Then, on the collapse of that star, they became locked into our planet at the phase of our planet’s formation billions of years ago. And of all the billions of tons of carbon that existed within our planet, only a very small proportion found themselves at the right place and the right time where the pressure, the temperature and the chemistry all aligned and they could bond together as a diamond. That’s a true moment of serendipity.
Next step: survival
They then have to survive. The oldest diamond dates to 3.5 billion years ago. Our earth was young, if we track the evolution of planet from that point forward, continents have formed and have been destroyed, oceans have opened, they have closed. Mountain ranges have risen, they have fallen and risen again. Deep in the earth, while all of this was unfolding above them, our diamonds existed as little vulnerable witnesses to this slower momentous evolution of our planet as it shifted over time. So, they really are survivors.
How do we have the honor of holding natural diamonds at all?
We know categorically that diamonds form roughly 140km (around 87 miles) within the earth and that we, as humans, can only dig to around 12.2km (7.5 miles) so there is no way for us to access these diamonds from the surface. The only reason we have access to these gems is because of a series of deep origin volcanic eruptions that transported them to the surface millions of years ago. There are several aspects of these eruptions that we need to understand.
Firstly, they are very rare
The last diamondiferous [yielding or containing diamonds] deep-origin volcanic eruption occurred 20 million years ago… and we’re not going to want another one anytime soon.
Secondly, they were extremely explosive events
and would cause quite a significant amount of damage. They are also incredibly powerful. They needed to be in order for them to get the diamond to the surface.
The third one is possibly the most important
They are actually quite small. The craters of these eruptions are not much larger than 1km (0.6 miles) in diameter, so it really is a case of hit or miss as to whether they could transport these gems to the surface at all.
Fourth, they are extremely volatile
As soon as that diamond is in contact with the magma and the pressure drops, those volatile agents are going to start attacking the diamond and dissolving it, possibly dissolving it to nothing at all. So, the fact that we have any diamonds at all making it to the surface is remarkable. A true miracle really.
Diamonds are gifts against all odds
In fact, of all the 7,000 known deep origin volcanic eruptions that could have brought diamonds to the surface, only 15% have been diamondiferous and less than 1% are economically viable to mine. There are around 37 large mine sites active today, so you can understand just how finite a material you have. Modelling suggests that in 45-50 years, 98% of all deposits will have been exhausted, therefore what we have now is all we have got. We need to treasure it. Diamonds are gifts against all odds.
Diamonds are the essence of life itself
Something I find particularly compelling is that the diamond story is equally our story. When diamonds started forming in the depth of the earth 3.5 billion years ago, our oceans were starting to tentatively pulse with the earliest forms of life; that’s both life and diamonds formed of carbon. Everything that lives and breathes requires carbon; you are 18% carbon by weight.
If a diamond is pure crystalline carbon in its most enduring state, as it was forming in the depths of the earth, it was like the seed, the essence of life itself. It’s the essence of what makes us human. In fact, a natural diamond has tracked our entire evolution on this planet. Put a diamond in my hand and I feel like I’m holding the hand of some learned sage and being taken on a journey through time.
As told to editor-in-chief of A Diamond is Forever, Lucy Frith
