A Once in a ‘Blue Moon’ Diamond to Make a Public Appearance

Photo credit: Cora International/Tino Hammid

Sometimes my job is pretty good. For example, on Friday I had the opportunity of seeing what is considered to be one of the rarest blue diamonds on the planet up close. At least that's what the owners of the stone say.

Appropriately named the “Blue Moon” (as in “once in a blue moon”), the diamond will make its first and likely only public appearance at the Natural History Museum of Los Angeles County in an exhibition from September 13 – January 6. 

Blue diamonds are rare enough but what separates this diamond from so many of its peers are its color saturation and shade, its clarity and its size, said Suzette Gomes, CEO of Cora International, a diamonds and jewels manufacturer known for working with statement diamonds. . The 12-carat cushion-cut diamond has been given a color grading of “fancy vivid” with an “internally flawless” clarity grading from the Gemological Institute of America. 

In addition, its color was further tested under ultraviolet light by the Smithsonian Institution under the supervision of Jeffrey Post, curator of the National Gem and Mineral Collection. The trace element Boron within the carbon structure of the stone is responsible for the color of a blue diamond. Boron also produces unique phosphorescence red glow under ultraviolet light.

Under ultraviolet light testing the gem produced an orangey-red glow for 20 seconds, longer than most blue diamonds, showing that the blue in the Blue Moon diamond is true and saturated throughout the stone with no other colors—such as grey, which is common for blue diamonds, Gomes said. Also, blue diamonds are known to exhibit a blue-green glow under ultraviolet light.

“What’s exciting is that the phosphor is orange red. That for us was a big thing because it gives you the purity of the diamond,” Gomes said on the other side of a desk with the Blue Moon between us on a grey felt tray inside Cora’s office in New York. “Other blues also glow phosphor red but it doesn’t last as long.… This was orange red for 20 seconds.”

There is no one more excited about this gem than Gomes who has called the Blue Moon her career highlight and a privilege to work with. Few have spent more time with the gem as well. 

“The fact that you could buy it rough, plan it and cut it is special,” she said. “This is a billion years old and it’s going to be here long after we’re gone. That’s the beauty of diamonds.”

Another thing that makes this diamond interesting is that it was a recent discovery. The Blue Moon was produced from a 29.62-carat rough diamond unearthed at the Cullinan mine in South Africa in January. The mine is known for producing the most blue diamonds in the world but these gems still only accounts for 0.1 percent of its total diamond output, Gomes said. As mentioned earlier, its clarity and color makes the gem even rarer. 

Cora acquired the rough for approximately $26 million in February and went right to work, finishing the piece only three weeks ago. All of the testing results from the Smithsonian and GIA were not completed as of Friday. 

The fact that the origin of the diamond is known makes this special as well, Gomes said.

“A lot of time with diamonds you don’t know what the origin is,” she said. “Someone has a one-carat vivid blue that their grandmother had and nobody knows where it comes from.”

The Blue Moon in the Cora International office. Photo credit: Anthony DeMarco

Sitting flat on a pad under normal office lighting didn’t provide the best view of the diamond but its shade of blue is unmistakable. Unlike the Hope Diamond, which has a blue that is deep, dark and rich, the Blue Moon is closer to an aqua blue. Gomes refers to it as "ocean blue." The facets appear as if they are wavelets on water. Finally, it’s transparent. You can see clear through the diamond. So picture a lake with sunlight dancing on its rippled surface and that is the color of the Blue Moon.  

Gomes said the cushion cut makes it most ideal to be used as a brooch or a ring, although she would display it on a wall as art. 

Gomes refuses to discuss its value and will not compare it to other stones. But I can. The largest known fancy vivid, flawless diamond (one grade over the IF clarity grade the Blue Moon received) is a pear-shaped, 13.22-carat stone purchased by the Harry Winston luxury jewelry brand for $23.8 million at Christie’s Geneva in April. Renamed the “Winston Blue,” the nearly $1.8 million-per-carat price paid is a world record for a blue diamond.

Gomes said she would rather focus on getting the Blue Moon to L.A. for the exhibition at the Natural History Museum. 

“We just want to get through the exhibition in the hope that it raises its profile because they are not the level of the Smithsonian,” she said. “I want to help them. What they do is awesome and they always struggle for money. They need funding and this will raise their profile too so it’s good for everyone.”

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