Petra Puts 39-Carat Blue Diamond Up for Sale

London—Petra Diamonds Ltd. has released details on the sale process for the nearly-40-carat blue diamond it recovered from the Cullinan mine in April, a remarkable stone expected to sell for upward of $50 million.

Viewings of the 39.34-carat, Type IIb stone will take place throughout June and into early July, including a stop in New York from July 7-9.

Tender bids are scheduled to close on or around Monday, July 12 at 10 a.m. EDT. 

In an interview with National Jeweler last week, George Togholian, a gemologist at L.J. West Diamonds, compared the 39.34-carat diamond to another big chunk of blue rough mined at Cullinan in January 2014—the 29-carat stone that became the $48.5 million “Blue Moon of Josephine.”  

New York-based Cora International cut that stone, and Togholian, who worked as a gemologist and consultant for the company then, helped with the planning process.  

Though he has not seen the 39.34-carat rough diamond in person yet, he said in pictures it looks “very similar” to the rough that produced the Blue Moon, possessing the color and texture specific to blues from Cullinan. 

“This is a special tone of blue. It’s not comparable to any other diamond that comes to auction,” Togholian said. 

“In my opinion, these are the best of the blues. This is on another level.”

While he declined to share his guess as to the diamond’s sale price, Togholian did note the 39-carat rough probably will deliver about a 40 percent yield—the yield for blues and pinks is generally less than yellow or white diamonds because the material is not as smooth, he noted—which means a polished diamond of about 15 to 16 carats. 

That’s 3 to 4 carats larger than the 12.03-carat Blue Moon of Josephine, which still holds the world auction record for highest-grossing gemstone per carat at $4 million.

Joseph Namdar, of Namdar Inc., described the 39.34-carat blue rough as a “very special diamond” that is “thought to be one of the purest blues to ever be mined.” 

While noting bidding is unpredictable, he put the rough diamond’s sale price at $55 million to $65 million.

Petra Diamonds operates three underground diamond mines in South Africa—the Cullinan, Finsch, and Koffiefontein—as well the open-pit Williamson mine in Tanzania. Williamson has been on care and maintenance since April 2020. 

The Cullinan mine has produced a number of famous diamonds, including, of course, the 3,106-carat Cullinan, the rough that produced the 69-carat Taylor-Burton Diamond, and the aforementioned 29-carat blue rough that became the Blue Moon of Josephine. 

Anyone interested in scheduling a viewing of the 39.34-carat blue diamond should contact Petra’s Group Head of Sales and Marketing Greg Stephenson at diamondsales@petradiamonds.com or +27 836 379 849.