The World’s Most Expensive Diamonds, and What Made Them Priceless

The most expensive diamond ever sold at auction is the Pink Star, a 59.60-carat Fancy Vivid pink that sold for $71.2 million at Sotheby’s Hong Kong in April 2017. The other record holders are almost all colored diamonds too, because vivid pink and blue are far rarer than the finest colorless stones.

Size alone does not make a diamond priceless. A 92-carat colorless diamond with the top color and clarity grades, La Légende, sold at Christie’s in 2017 for about $15 million. A blue diamond one-eighth its size sold for three times as much. What the record prices reward is rarity of color, and the reasons a diamond turns pink or blue are as unusual as the prices.

The record sales at a glance

Prices include buyer’s fees as reported at the time. The Oppenheimer Blue, a 14.62-carat Fancy Vivid blue sold at Christie’s Geneva in May 2016, also belongs on this list; published figures for it range above $50 million depending on currency and fees.

The Pink Star

The Pink Star was mined by De Beers in South Africa in 1999 and weighed 132.5 carats in the rough. It was cut to 59.60 carats and graded Fancy Vivid pink by GIA. It was first sold at Sotheby’s Geneva in 2013, but the buyer did not pay and the stone returned to the auction house. In April 2017 it sold in Hong Kong for $71.2 million, about $1.2 million per carat, to Chow Tai Fook.

Sale details are from GIA’s report on the 2017 auctions and Wikipedia’s Pink Star entry.

Why pink diamonds cost the most

Most colored diamonds owe their color to a trace element: nitrogen makes a diamond yellow and boron makes it blue. Pink is different. GIA’s research found that the color of 99.5% of pink diamonds comes from distortion in the crystal structure itself, created by plastic deformation deep in the earth, and that the color usually sits in thin parallel bands called glide planes or graining. Only a tiny share of diamonds turn pink this way, and only a tiny share of those are richly colored.

For decades almost all of them came from one place. The Argyle mine in Western Australia produced roughly 90 to 95 percent of the world’s pink and red diamonds until it stopped production on 3 November 2020. With Argyle closed, the supply of new vivid pinks has shrunk sharply, which is why their prices have kept rising.

The cause of pink color is from GIA’s research on pink diamonds; Argyle’s share and closing date from Wikipedia’s Argyle mine entry.

The blue diamonds: the Blue Moon and the Hope

Blue diamonds take their color from traces of boron in the crystal. The Blue Moon of Josephine, 12.03 carats and Fancy Vivid blue, sold at Sotheby’s Geneva in November 2015 for $48.4 million, at the time a record price per carat for any diamond: roughly $4 million a carat.

The most famous blue of all has never been sold at auction in modern times. The Hope Diamond, 45.52 carats and graded fancy dark greyish-blue by GIA, was donated to the Smithsonian by the jeweler Harry Winston in 1958 and has been on display in Washington ever since. After exposure to ultraviolet light it glows red for a few moments, an effect of boron and nitrogen together. Its famous curse is a legend; historians regard the stories of misfortune as embellishments that added to its fame.

Details are from Wikipedia’s entries on the Blue Moon of Josephine and the Hope Diamond.

The diamonds that will never be sold

Some of the most valuable diamonds have no price because they will never come to market. The Cullinan, found at the Premier Mine in South Africa on 26 January 1905, weighed 3,106 carats in the rough and remains the largest gem-quality rough diamond ever found. Its two largest stones, Cullinan I (530.4 carats, the Great Star of Africa) and Cullinan II (317.4 carats), are set in the Sovereign’s Sceptre and the Imperial State Crown among the British Crown Jewels. The Koh-i-Noor, now 105.6 carats, is set in the Crown of Queen Elizabeth the Queen Mother and displayed in the Jewel House at the Tower of London.

Weights are from Wikipedia’s entries on the Cullinan Diamond and the Koh-i-Noor.

What this means for a diamond you would actually wear

Record diamonds are priced on rarity: a color almost no diamond has, from a mine that no longer produces, in a size that may never be found again. None of that changes what a diamond is. A lab-grown diamond is the same crystal of carbon, with the same hardness and the same fire, grown in weeks instead of formed deep in the earth over an immense span of time. What it does not carry is the auction premium for geological accident.

That is the honest trade. If you want a stone whose value lies in its rarity, it is mined and colored and priced like the table above. If you want the look, the light and the durability of diamond, a certified lab-grown stone gives you all three for a fraction of the cost. Our lab-grown diamond guide explains the difference in detail, and our article on lab-grown diamond durability covers how they wear.

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