95-carat, Type IIa diamond found in Angola
January 29, 2014
A 95.45-carat piece of rough sits behind a semi-circle of other diamonds recently recovered from Lucapa’s BLK_19 alluvial bulk sample. The diamonds are, from left, 3.35, 3.90, 2.55, 1.75, 1.75, 1.45, 1.20 and 1.05 carats.
Perth, Western Australia--Mining company Lucapa has unearthed a 95.45-carat diamond from its Lulo Diamond Concession in western Angola, the second-largest stone recovered to date at the alluvial deposit.
Lucapa Diamond Co. Ltd. described the gem as “exceptional,” with an irregular but roughly equant shape. A Yehuda ZVI colorimeter confirmed the stone was Type IIa, which means it is among the rarest diamonds as Type IIas contain no nitrogen or boron impurities.
The company notes that the diamond has not been cleaned, and that is expects its appearance and clarity to improve dramatically after iron staining is removed.
Currently, the diamond’s color is classified as D/E, meaning it is an exceptional white diamond, though the stone comes up as a brown on the colorimeter. Lucapa said cleaning the stone and re-testing it with the colorimeter should resolve the classification.
The only stone larger recovered by Lucapa from the Lulo deposit was a 131.4-carat diamond found in 2012. That stone also was Type IIa.
In addition, the 95.45-carat rough diamond is the largest of 66 diamonds weighing 206 carat recovered to date from the deposit’s BLK_19 alluvial bulk sample, and follows the recovery of a 32.2-carat Type IIa diamond earlier this month. Other large diamonds to emerge from this area include a 10.95-, 7.65-, 7.3- and 5.65-carat diamond.
Lucapa’s Lulo Diamond Concession contains a major kimberlite field and diamond-bearing alluvials located along the Cacuilo and Lulo rivers. It is about 150 kilometers (93 miles) west of the Catoca diamond mine, which Russian miner Alrosa operates in conjunction with Endiama, the diamond company owned by the Angolan government, and other companies. The concession is located on the same geological structure, the Lucapa Graben.
Lulo is a joint venture between Perth-based Lucapa and Endiama, which is the exclusive concessionary for diamond mining rights in Angola.