Mining company Gem Diamonds said it has unearthed a 478-ct. diamond that has the potential to yield one of the largest flawless D color round polished diamonds in history.

The diamond was discovered in the Letšeng Mine in the southern African country of Lesotho. The mine is operated as a partnership with the Government of the Kingdom of Lesotho. The diamond was discovered Sept. 8 and the mining company announced the discovery Monday.

The diamond was transferred to Antwerp where it underwent acidisation and provisional analysis, Gem Diamonds said in a statement. It was determined to be a type II D color diamond. The company added that the diamond is of “outstanding clarity with no inclusions visible in its rough form. It has the potential to yield one of the largest flawless D color round polished diamonds in history.” (View video of the diamond.)

The diamond, which is yet to be named, ranks as the 20th largest rough diamond ever to be recovered. It is the third significant recovery from the Letšeng Mine in as many years, following the 603-ct. Lesotho Promise and the 493-ct. Letšeng Legacy recovered in 2006 and 2007 respectively. Including the 601-ct. Lesotho Brown, recovered in 1960, the Letšeng Mine has now produced four of the world’s 20 largest rough diamonds and the three largest diamonds recovered this century.

“Preliminary examination of this remarkable diamond indicates that it will yield a record breaking polished stone of the very best color and clarity,” Clifford Elphick, chief executive officer of Gem Diamonds. “With a further 45 years of life remaining, we expect Letšeng to make history for many years to come.”

JCK