A Sierra Leone mining operation discovered a 476-carat rough diamond at the Meya deposit in the nation’s Kono district last week, its owner announced Friday.

Meya Mining, a subsidiary of Namibia-based conglomerate Trustco Group, found the diamond, which ranks as the fifth-largest rough ever found in Sierra Leone, according to Rapaport records.

“Any value indication of the diamond is pure speculation at this stage, as the diamond has not yet been examined and assessed by the necessary experts,” Trustco said.

Meya holds a four-year exclusive diamond-exploration license in the Kono district. It found the stone in an area spanning from the Kamara Gbense to the Tankoro chiefdoms, and intends to sell it through an international auction, the parent company explained.

On the same day, Meya also unearthed diamonds weighing 27.93 carats and 19.70 carats in Kono, Trustco added.

Trustco, whose shares are listed in Windhoek and Johannesburg, has interests in insurance, finance and natural resources. It bought 51% of Meya Mining in August 2016 from Germinate Sierra Leone for $1 million, but that price could rise to about $26 million if the asset meets certain performance targets.

The company’s announcement follows the discovery of the 709-carat Peace Diamond by artisinal miners in the Kono district in March. The Rapaport Group will auction that diamond — believed to be the 14th-largest in history — in New York on December 4.

Lower image shows Sierra Leone Minister of Mines and Mineral Resources Minkailu Mansaray with the 476-carat diamond.