Pink diamonds are a rare and valuable gem, with some fetching more than $2 million per carat. Unlike blue and yellow diamonds, which get their color from impurities, pink diamonds’ unique color comes from geological processes that deform the crystal structure. The Argyle Formation, located in Western Australia, is where these highly sought-after gems were found.
This formation 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. The process of forming pink diamonds occurs when tectonic plates collide under intense pressure and temperature conditions, causing pre-existing diamonds to take on different pink tones. This happened as the Nuna supercontinent began to break apart 1.8 billion years ago.
The diamond-bearing rock was pushed closer to the surface during this process, making it accessible for mining by Rio Tinto, the company that owned and operated the Argyle mine for 37 years. During its operation, the mine produced over 865 million carats (172 tonnes) of rough diamonds, including 90% of the world’s pink diamonds. However, due to a decline in diamond supplies and unfavorable economic conditions, the mine closed in 2020.
