Mineral Sciences - Blue Moon Diamond | Natural History Museum of Los Angeles

The Blue Moon Diamond: an exceptional 12 carat Fancy Vivid Blue diamond on temporary exhibit at NHM.

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Blue Moon Diamond

One of the Rarest Gems Worldwide

12-carat, Internally Flawless, Cushion Cut, Blue Diamond on Exhibit


At the Natural History Museum of Los Angeles County

September 13, 2014 until January 6, 2015


The 12-carat, Internally Flawless, Fancy, Vivid Blue Moon Diamond. Copyright: Cora International. Photo by Tino Hammid.

The Natural History Museum of Los Angeles County (NHM) has unveiled one of the rarest stones, a 12-carat Fancy Vivid blue diamond, which is internally flawless. The Blue Moon Diamond was housed in a special, temporary exhibition in the Gem Vault from September 13, 2014 until January 6, 2015.

The Blue Moon Diamond has been categorized as an extremely significant find – and one of the newest and rarest stones currently worldwide – due to its unique color, clarity, and size. Cut from a 29.6-carat rough, the internally flawless gem is fashioned in a cushion-cut shape at a noteworthy 12 carats. Diamonds with a strong saturated color represent only a tiny percentage of all natural diamonds – and only a minute percentage of all natural color diamonds are blue, making the Blue Moon Diamond exceptional. The stone was found in the Cullinan mine, northeast of Pretoria, South Africa, which is known for discovering some of the most recognized blue and other color diamonds in the world.

To celebrate the unveiling of the finished stone, NHM is hosting a special exhibition from September 13, 2014 through January 6, 2015. Visitors will be able to view the Blue Moon Diamond in person and learn more about the stone. The rare gem is on loan from Cora International, a world leading manufacturer and supplier of white and fancy colored diamonds.

“Fancy vivid blue diamonds are extremely rare and the Blue Moon is no exception. It is a historic stone that is one of the rarest gems with this color and in this size to be found in recent history,” said Suzette Gomes, CEO of Cora International. “After seeing the stone’s color and understanding its significance, it was fitting to name it the Blue Moon Diamond as not only its shape is reminiscent of a full moon, but the metaphor for the expression is exactly what one could say about the occurrence and existence of such a gemstone.”

Fancy colored diamonds are more valuable and rarer than the colorless varieties. Unlike most minerals, whose color is determined by some intrinsically colored chemical elements, like copper in most blue or green minerals, diamonds obtain their colors from so-called “color centers”. They are single or multiple non-carbon atoms that replace carbon in the structure of the diamond, causing a disturbance in the structure and sometimes giving rise to the color. The distinctive blue color in diamonds is attributed to trace amounts of the element boron in the crystal structure. Minute traces of boron are required to create the coloration. Less than one boron atom per million carbon atoms is sufficient to produce the blue coloration.

This special exhibit fits within the Museum's mission to enhance discovery of the natural world through furthering the future of diamond research. "Blue diamonds are among the rarest of all natural colored diamonds,” said Dr. Eloïse Gaillou, curator and diamond expert at NHM. “The exhibit will provide a once-in-a-lifetime opportunity for visitors to see one of the world's most exquisite blue diamonds in person." Eloïse Gaillou was part of the team to examine the Blue Moon Diamond in August at the Smithsonian Institution. “Blue diamonds of this size and of known localities are extremely rare to come across; we had the chance to analyze it, and the data acquired will enable us to understand more about the formation process and the physical properties of these unusual gems”, says Gaillou.

The Blue Moon Diamond during scientific testing at the Smithsonian Institution. The equipment behind the diamond is a phosphorescence spectrometer. Copyright: NHM. Photo by Eloïse Gaillou.


The Blue Moon Diamond displays a strong red phosphorescence after exposure to ultraviolet light. Copyright: Cora International. Photo by Tino Hammid.


To showcase the significance of this stone, the Gemological Institute of America (GIA) has made a monograph of The Blue Moon Diamond. According to the GIA, a monograph offers detailed documentation of outstanding gems in book format, offering a holistic perspective on their character and significance. The GIA Monograph report “fleshes out the details of a gem’s story, highlighting the features that elevate the gem to the realm of the truly exceptional.” The GIA has also written a special letter for this stone due to its rarity and beauty.

During the later portion of the 19th century, De Beers Consolidated Mines Ltd. controlled almost all of the world’s diamond production. During the time of De Beers diamond dominance (1888), very few sources for diamonds existed that could directly challenge the production of De Beers. This changed when Thomas Cullinan discovered the Cullinan mine in 1902, which at that time was named the Premier mine. Established on the second largest kimberlite pipe by inherent value, the Premier mine gained immediate prominence as a quality producer of large colorless diamonds and also rare blue diamonds. Annual production from the Premier mine was the largest in the world for the mine’s first decade of operation. Perhaps one of the greatest finds in the mines history is the Cullinan diamond. The Cullinan diamond is the largest colorless diamond ever discovered with a weight of 3,106 carats (~ 600 grams) which has since been cut and polished into nine major stones, including 96 minor stones! Two of them currently reside within the Crown Jewels of the United Kingdom.