Pink diamonds have long been objects of fascination and wonder, not just for their striking hue and the prestige that comes with their rarity, but also due to the mysteries surrounding their formation. Revered as some of the world’s most expensive gems, the narrative of pink diamonds took an intriguing twist with recent revelations from scientists.
Of all the pink diamonds ever found, an astounding 90 percent or more originated from the Argyle mine, nestled in the remote northwest of Australia. What makes the Argyle mine even more peculiar is its geographical location. While most diamond mines are situated at the heart of continents, Argyle is an exception, sitting on a continent’s edge. This peculiarity has only fueled the enigma behind the prolific production of pink diamonds at this site.
A ground-breaking study, recently featured in the renowned journal, Nature Communications, might just have the answers we’ve been seeking. Australian researchers posit that the pink diamonds’ journey to the Earth’s surface is linked to the disintegration of the planet’s first supercontinent approximately 1.3 billion years in the past.
Hugo Olierook, a prominent researcher at Curtin University in Western Australia, took the lead in this fascinating study. In shedding light on the process, Olierook elucidated that forming pink diamonds requires three crucial components.
The primary component is carbon, and it’s not just about having carbon, but its location matters immensely. For carbon to be a contender in the creation of a diamond, it has to be deep within the Earth, specifically deeper than 150km. Anything shallower, and it turns into graphite, the material found in everyday pencils. As Olierook jestingly remarks, graphite may not be one’s first choice for an engagement ring setting.
Next, we have the element of pressure, and it’s not just any pressure – it has to be just right. Pressure holds the power to morph otherwise clear diamonds, giving them their distinctive pink hue. Olierook describes this intricate process in simple terms: “A little push turns it pink. Push too hard, and it becomes brown.” This explains why Argyle also housed diamonds of a less valuable brown shade.
However, these two components – carbon and pressure – were always part of the known equation. What remained elusive was the third ingredient, the very catalyst that would propel these diamonds from the Earth’s depths to its surface.
To pinpoint this missing link, researchers embarked on an intricate examination of an Argyle rock sample, graciously provided by the mine’s proprietor, the mining behemoth, Rio Tinto. Employing a laser, with a width finer than human hair, they probed minute crystals within the sample. This meticulous examination allowed them to measure the age of elements in these crystals. The revelation was astonishing: Argyle was dated to be 1.3 billion years old. This meant the diamonds rose to the surface 100 million years later than previously believed.
This timeline aligns perfectly with the disintegration of the world’s inaugural supercontinent, Nuna (or Columbia). A time when the Earth’s landmasses were merged into one colossal entity. It was during this era, about 1.8 billion years ago, that Western Australia and northern Australia collided, infusing color into the diamonds. As Nuna began to fragment half a billion years later, the remnants of this past collision played a pivotal role. Magma erupted through these old “scars”, akin to a cork popping off a champagne bottle, ferrying the diamonds to the surface.
Luc Doucet, a co-author of the study, drew attention to the magnitude of this volcanic event, stating that such an explosive force has never been observed in human history. This eruption was so potent that it propelled the diamonds nearly at the speed of sound.
The significance of these findings cannot be overstated, especially for diamond prospectors. For centuries, the quest for diamonds was centered on the heartlands of huge continents. However, this new understanding could pave the way to exploring old mountain belts near the continental edges, potentially heralding a new era of pink diamond discovery. Possible locations for this next “pink diamond paradise” include Canada, Russia, southern Africa, and even parts of Australia.
Despite the groundbreaking nature of these revelations, it’s important to approach with cautious optimism. John Foden, a diamond connoisseur from the University of Adelaide who wasn’t involved in this research, acknowledges the validity of the study’s findings regarding Argyle’s age. However, he cautions that while other diamond-rich regions have been linked to Nuna’s breakup, they haven’t yielded pink diamonds. This implies that the unique pink hue might be an exclusive trait of Argyle.
In concluding, one cannot help but lament the closure of the Argyle mine in 2020, attributed to a myriad of financial challenges. With the mine’s closure, the already rare pink diamonds could become even scarcer, likely driving their value even higher.
This study not only unravels the mystery of the pink diamonds but also underscores the intricate dance of nature’s elements over billions of years, leading to the creation of one of Earth’s most treasured gems.