( CNN ) -- A diamond unearthed in the southern African nation of Lesotho could yield one of the largest and highest quality round polished diamonds , according to a statement Monday from company that found it . A mining company unearthed this 478-carat diamond in the southern African nation of Lesotho . Experts in Antwerp , Belgium who analyzed the 478-carat stone determined it to be of the highest color grading available for a white diamond , said a statement from Gem Diamonds Ltd. , the company that found the stone . `` What makes it more remarkable is the color and quality of this stone , '' said diamond consultant Neil Buxton . `` It 's a D color , which is the highest possible graded color you can get , and we believe there is a chance -- a very good chance -- of getting a 100-carat plus '' round stone with the highest color and clarity rankings . The company said such a stone would `` to the best of our knowledge '' be `` the first one in history . '' Watch more on the diamond » . The diamond , which was found in September , ranks as the 20th largest rough diamond ever found , but is not the biggest ever taken from the Letseng Mine , which is co-owned by Gem Diamonds Ltd. and the Kingdom of Lesotho , a country of 2.1 million that is surrounded by South Africa . Two bigger stones -- 603 and 493 carats -- were found in the mine in 2006 and 2007 , respectively , the company said . A 601-carat diamond was mined there in 1960 , it said .
Diamond could yield one of the largest and highest quality round polished 0 . 8 stone allowing it to be of the highest color grading available . Diamond found in Diamond Mine , in Lesotho .