Discover the Rarest and Most Expensive Blue Diamonds

Learn more about the rare and coveted blue diamond.

Early History of the Blue Diamond

The earliest known blue diamonds were found in the Kollur mine in the Golconda region of India. Famous blue diamonds from this region include the Idol’s Eye (15th century) and the Hope Diamond (17th century). Historically, blue diamonds were recovered mainly in India and Brazil. For the last 100 years, they have also been randomly and sporadically found in the Premier Mine (since renamed the Cullinan Mine) in South Africa. Blue diamonds make up much less than 0.1 percent of all diamonds recovered at this mine, and to discover one annually of quality and size is an extremely unusual occurrence. Like other colored diamonds, blue diamonds are valued based on the clarity and intensity of the color first, followed by the size and finally the cut quality.

Blue diamonds are among the rarest colored diamonds. While technically red diamonds are the rarest, there are very few that ever sell in the secondary market. Blue diamonds also can grow to much larger in size since most red diamonds are only 0.5 to 1 carat in size. Blue diamonds get their color from the element boron but nitrogen also plays a role in determining the intensity of the color. The Boron replaces some of the carbon in the diamond crystal structure and can produce anything from a very light hint of blue to a deep dark blue color.

Blue attracts and fascinates people and this is no exception when for diamonds. Fancy vivid blue diamonds have a beauty that is incomparable to that of any other gem. They are greatly admired and eagerly sought after by collectors and connoisseurs alike. Often the blue color is not evenly distributed, and on occasion almost entirely absent, therefore it is a professional challenge for the diamond cutter to encapsulate a beautiful pure even blue color. He will spend months studying the rough stone in order to guarantee the greatest standards of proportionality, color and beauty.

Blue Diamond Grading

A blue diamond is graded and classified based on several key criteria like white diamonds including color, clarity, cut, and carat weight. Color grading of blue diamonds is the most important aspect influencing pricing for a blue diamond. Colors are classified by the hue or the actual color of the diamond including secondary hues such as greenish-blue or grayish-blue. Tone is another factor that can vary from very light to very dark. Finally the saturation is the strength of the color. A blue diamond with high saturation or more vivid and more desirable in the market. Clarity, cut and carat weight grading is the same as other diamonds.

The Gemological Institute of America (GIA) uses the following categories to describe the color of blue diamonds:

Fancy Light Blue
Fancy Blue
Fancy Intense Blue
Fancy Vivid Blue
Fancy Deep Blue
Fancy Dark Blue

Blue diamonds that are graded of Fancy Vivid Blue are the most intense in color and are also the coveted. Fancy Vivid specifically describes a blue diamond that is medium to dark in tone and strong to very strong in saturation. In a past GIA study of 462 blue diamonds, only 1% were Fancy Vivid.

Type IIb Blue Diamond

A Type II diamond is a classification for a diamond based on the chemical composition. Type II diamonds have extremely low or complete absence of nitrogen impurities. The lack of impurity gives Type II diamonds exceoptional transparency and fewer inclusions than Type I diamonds.

Type IIb diamonds contain boron which give them blue or grayish-blue color. The intensity is based on the amount and distribution of boron. Unlike other diamonds, Type IIb blue diamonds are semiconductors and can conduct electricity and are even rarer than Type IIa diamonds. The Hope Diamond is an example of a famous Type IIb diamond.

Most Famous Blue Diamond: The Hope Diamond

The Hope Diamond is a 45.2 carat fancy deep greyish blue Type IIb diamond and is valued at over $200 million. The Hope Diamond is thought to have been obtained in India in 17th century by French Gem Merchant Jean-Baptiste Tavernier. It started out as a 112 carat diamond. It was sold to King Louis XIV and recut into a 69 carat stone called the "French Blue" and became part of the French Crown Jewels. The diamond disappeared during the French Revolution but reappeared in London in the early 19th century. It was then recut to 45.52 carats and named the Hope Diamond after Henry Philip Hope. Harry Winston purchased the Hope Diamond in 1949 when he purchased the entire estate of Mrs Evalyn Walsh McLean. McLean purchased the diamond from Cartier in 1911. The Hope Diamond was donated to the Smithsonian by Harry Winston in 1958.

Most Expensive Blue Diamonds

Sotheby's has sold some of the rarest and most expensive blue diamonds during the last 10 years. Learn more about six of the most unique and rare blue diamonds.

1. De Beers Blue $57.5 million

The most expensive blue diamond sold by Sotheby's in the last 10 years is the De Beers Blue that sold for $57.5 million in 2022. The De Beers Blue diamond is a step cut 15.10 carat Fancy Vivid Blue, Internally Flawless and a Type IIb diamond. The 15.10 carat Fancy Vivid Blue diamond was cut from an exceptional rough stone discovered in April 2021. The De Beers Blue diamond is the largest vivid blue diamond ever to appear at auction and the largest internally flawless step cut vivid blue diamond that the Gemological Institute of America (GIA) has ever graded. The combination of this diamond size, saturated color and Internally Flawless clarity grade make it truly unique. Blue diamonds of this importance are exceptionally rare, with only five examples over 10 carats ever having come to auction, none of which have exceeded 15 carats, making the appearance of this flawless gem a landmark event in itself.

Perfect according to every critical criterion, The De Beers Blue has achieved the highest rankings under each of the standards by which the quality of a colored diamond is judged. It has been graded Fancy Vivid Blue by the Gemological Institute of America (GIA) – the highest possible colour grading, awarded to no more than 1% of blue diamonds submitted to the GIA. It also boasts exceptional clarity, having been declared Internally Flawless by the GIA; in addition to which, it was found to have excellent polish and to be of Type IIb, a rare category which represents less than 0.5 % of all diamonds. Adding to the diamond’s allure is its classic step-cut – a style most associated with white diamonds – that is immensely sought-after in rare colors.

2. Blue Moon of Josephine, $48.5 million

In 2015, Sotheby's sold the Blue Moon, a fancy vivid blue diamond weighing 12.03 carats for $48.5 million. While the Blue Moon diamond is now the second most expensive blue diamond sold by Sotheby's, it still holds the record for the highest price per carat for a blue diamond at just over $4 million. The diamond was purchased by a private collector in Hong Kong that renamed the diamond the Blue Moon of Josephine. The blue diamond is natural color, internally flawless and a Type IIb diamond. The Blue Moon diamond was exhibited at the Natural History Museum of Los Angeles County, 13 September 2014 – 6 January 2015. The Blue Moon diamond was reportedly unearthed from the Cullinan mine in January 2014 as a 29.62 carat rough stone and is one of few diamnds to have been tracked precisely from the mine to the hands of its cutter.

“After seeing the stone’s colour and understanding its significance, it was fitting to name it the Blue Moon Diamond,” noted Suzette Gomes, CEO of Cora International. “Not only its shape is reminiscent of a full moon," she said of the cushion-shaped fancy vivid blue 12.03-carat diamond, “but the metaphor for the expression is exactly what one could say about the occurrence and existence of such a gemstone.”

3. The Memory of Autumn Leaves & The Dream of Autumn Leaves $42.1 million

In May 2017, Sotheby’s sold the ultimate in colored diamonds: Apollo and Artemis, since renamed to The Memory of Autumn Leaves and The Dream of Autumn Leaves, comprised of a blue diamond weighing 14.54 carats, internally flawless, type IIb, and a pink diamond weighing 16.00 carats, VVS2 clarity, type IIa. The stones were mounted as a spectacular pair of earrings, offered separately, on account of their extreme rarity, power and presence. Selling together for CHF57,118,750 ($57,425,478), they became the most valuable earrings ever sold at auction. The exceptional fancy vivid blue diamond earring sold for $42.1 million.

4. The Zoe Diamond, $32.6 million

The fourth most expensive blue diamond was another pear shaped diamond classified as a Fancy Vivid Blue diamond weighing 9.75 carats selling for $32.6 million in 2014. The diamond was including in the Collection of Mrs Paul Mellon. After 20 minutes of competitive bidding, Mrs Mellon’s magnificent and rare 9.75-carat fancy vivid blue diamond pendant sold for more than double its high estimate. The GIA certificate states the diamond is Fancy Vivid Blue, Natural Color, VVS2 clarity. Together with the original working diagram stating that the diamond may be potentially internally flawless. It was renamed The Zoe Diamond.

5. De Beers Millennium Jewel 4, $32.2 million

Sotheby's sold a 10.10 carat internally flawless blue diamond for $32 million in Hong Kong in April 2016. De Beers, together with The Steinmetz Group showcased an exceptional collection of eleven important blue diamonds to celebrate the Millennium in 2000. The De Beers Millennium Jewels were exhibit at London’s Millennium Dome. The oval-modified brilliant-cut diamond is natural fancy Vivid Blue and internally flawless and is inscribed De Beers Millennium Jewel 4.

The De Beers Millennium Jewels collection even instigated the "robbery of the millennium" when a ten-ton JCB digger broke thought the wall of the Dome only to find replaced replicas of the diamonds which were replaced a day earlier in preparation of the heist. The robbers, armed with sledgehammers, guns and grenades smashed through the gem’s armored casing before being detained.

6. Infinite Blue, $25.8 million

In 2023, Sotheby's sold the Infinite Blue Diamond for 198 million HKD or $25.8 million. This 11.28 carat radiant cut fancy blue vivid diamond is natural color, VS2 clarity and is a Type IIb diamond. This diamond is accompanied by a monograph expressing "To say the Infinite Blue is special cannot be overstated. The odds of finding a blue diamond is of the topmost rarity. This glorious and notable diamond is an example of what can occur when nature leads the way and humankind embraces the earth’s treasures—producing a gem of spirited light performance."

How to a Buy Blue Diamond at Sotheby's

Sotheby's often has impressive fancy blue diamonds and fancy vivid blue diamonds at auction. Sotheby's also often has a small selection of blue diamond jewelry available for immediate purchase on marketplace. If you would like to source a blue diamond for a ring or other jewelry creation, a salon specialist would be happy to assist. Sotheby's is also able to source incredible blue diamond jewelry creations from its global supplier network.

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