Pink diamonds are among the rarest and most valuable gems in the world, with some fetching prices of over $2 million per carat. The Argyle mine, located in a remote area of Western Australia, was responsible for producing over 865 million carats (172 tonnes) of rough diamonds, including 90% of the world’s pink diamonds.
Pink diamonds are unique because their color comes from geological processes that deform the crystal structure, unlike blue and yellow diamonds which get their color from impurities. This rarity adds to their allure and value in the gem market.
The Argyle Formation, where these diamonds were found, is located on the edge of a continent and is made of olivine lamproite rock, unlike traditional kimberlite formations. Researchers have determined that the formation is around 1.3 billion years old, shedding light on the conditions under which pink diamonds are formed.
Pink diamonds are created when tectonic plates collide under intense pressure and temperature conditions, causing pre-existing diamonds to take on different pink tones. This process occurred as the Nuna supercontinent began to break apart 1.8 billion years ago, creating the perfect conditions for pink diamonds to form in the Argyle Formation.
As a result of this discovery, Rio Tinto, the company that owned and operated the Argyle mine was able to extract a large quantity of brown diamonds from the area in addition to highly sought-after pink diamonds. However due to a decline in diamond supplies and unfavorable economic conditions, it closed down in 2020 after operating for 37 years.