Gem Diamonds Ltd. made its largest gem quality rough diamond find this year when it pulled a 198 carat piece of rough from its Letseng mine in the Kingdom of Lesotho last month, the latest in a line of 100 carat plus stones found this year. Lesotho is a small country located within South Africa.
The 198 carat rough diamond unearthed by Gem Diamonds Ltd. in late July from the Letseng mine in Lesotho. Photo courtesy of Gem Diamonds Ltd.
Roughly the size of a large strawberry, the stone is a Type IIa diamond and is described by Gem Diamonds as an “exceptional white, high quality diamond (that) displays no florescence.” A spokeswoman for the mining company said they cannot comment on what size of polished diamond the stone will yield nor the estimated price it will fetch. The rarest type of diamond on earth, Type IIa’s contain no measurable nitrogen or boron impurities, and colorless Type IIa stones are known for their exceptional color and clarity.
It is the third largest rough diamond declared this year, topped only by the 258.69 carat stone Lucara Diamond Corp. sold in July from the Karowe Mine in Botswana and the 239 carat stone it is offering in its next tender. In addition, the 198 carat white diamond is the largest gem quality stone to emerge from Letseng since August 2011, when the mining company found a 553 carat rough diamond.
Gem Diamonds operates Letseng in a 70-30 partnership with the Lesotho government. They also own the Ghaghoo mine in Botswana.
Another factor to consider is that Gem Diamonds is mining in Letseng’s satellite pipe again, which is historically the source of most of the mine’s large stones.
As Russell Shor, a senior industry analyst with the Gemological Institute of America, points out, it is a mine with quite a history.
While the 198 carat diamond is the largest stone to emerge from the mine this year, (and is actually the largest since 2011) this also is the mine that produced the 603 carat Lesotho Promise, the 15th largest diamond ever found, the 493 carat Letseng Legacy, a 553 carat diamond in 2011 and a 478 carat diamond in 2008.
“The latest find,” Shor observes, “is not unusual for this particular mine.”
He adds that the Cullinan mine, which produced the 122.52 carat blue stone this year that could shatter the world rough diamond price record, is also historically, a prolific source of significant stones.
It is the source of one fourth of all diamonds more than 100 carats in size, including the largest rough diamond discovered to date, a 3,106 carat piece of rough aptly named the Cullinan diamond.