It’s common knowledge that diamonds are the world’s most prized and expensive gemstones, with the sparkling rocks adorning everything from engagement rings to Jennifer Lopez’ facial exfoliator. You’ve heard of famously extravagant diamonds like the Hope Diamond and Koh-i-Noor. These exquisite blue and colourless diamonds are worth hundreds of millions to billions of dollars apiece.
However, these rare specimens are valued far above the usual price: the cheapest of blue diamonds fetch $45,000 per carat, while the common white diamond retails for a comparatively meagre $1,100 per carat – so what type of diamond is the most expensive in the world?
Red diamonds are the rarest and costliest of gemstones, valued at a whopping $300,000 to over $1 million per carat. In fact, only 30 red diamonds of true gem quality are currently believed to exist in the world. These elusive stones see a price per carat markup 300–400% higher than the next most expensive types of diamond: pink diamonds and blue diamonds.
The 6-7 figure price tag is justified thanks to the red diamond’s rarity – only a few are discovered each year, and of the scant number that are mined, rarely do they reach 0.5 carats in size. Only 5 red diamonds in the world are known to be over 5 carats.
The majority of these gemstones originate from the Argyle Diamond Mine in East Kimberley, Western Australia, the world’s biggest producer of diamonds by volume and the source of 90% of pink and red diamonds. However, red diamonds have also been discovered in Brazil, Russia, India, Russia and parts of Africa.
Red diamonds share the same inherent mineral structure with colourless diamonds, but opinions are still divided on what gives them their distinctive red hue. Coloured diamonds indicate either chemical impurities or structural abnormalities, and the most commonly accepted explanation is that red diamonds fall under the latter category due to the immense pressure they are placed under during formation. They are thought to be extremely dark pink diamonds and are best viewed under natural daylight to show off their splendid colour.
Naturally-occurring diamonds of pure red colour, although ideal, are rare. Most red diamonds fall on a spectrum of hues ranging from purple-red to brown-red and orange-red. On the minute level, this precious stone’s value is based on its distinctive red colour, the brightness or darkness of its tone, the amount of secondary colours present and its clarity (from Flawless to Included).
The Moussaieff Red Diamond
The largest and most famous red diamond in the world is the Moussaieff Red Diamond, named after its current owner, London-based jeweller Shlomo Moussaieff. Weighing in at 5.11 carats, it was sold at auction for a cool $8 million in 2001, coming to a per carat value of 1.56 million. Also known as the Red Shield, it has an estimated current value of $20 million and boasts internally flawless clarity. This rare beauty was discovered by a farmer in Brazil’s Abaetezinho River during the 1990s, weighing 13.90 carats in the rough.
The Kazanjian Red Diamond
Previously known as simply Red Diamond, the second-largest red diamond in the world weighs 5.05 carats and was discovered in South Africa in 1927. Interestingly, its location today is unknown.
The DeYoung Red Diamond
Housed in the collection of the National Museum of Natural History of the Smithsonian Institution, the 5.03 carat DeYoung red diamond is the third-largest in the world and is valued at approximately $5 million. It was named after a previous owner, Boston jeweller Sidney DeYoung, who donated it to the museum.
By Jennifer Luu