(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.
How many carats is the stone? What size is the diamond? What could yield one of the highest quality stones? What was found at a mine in Lesotho? What could the diamond yield? What is the carat weight of the gem? Where was the diamond mine found? Where was the diamond found? How many carats was the stone?
478-carat 478-carat diamond unearthed in the southern African nation of Lesotho 478-carat diamond and highest quality round polished 478-carat African nation of Lesotho southern African nation of Lesotho. 478-carat
question: How many carats is the stone?, answer: 478-carat | question: What size is the diamond?, answer: 478-carat | question: What could yield one of the highest quality stones?, answer: diamond unearthed in the southern African nation of Lesotho | question: What was found at a mine in Lesotho?, answer: 478-carat diamond | question: What could the diamond yield?, answer: and highest quality round polished | question: What is the carat weight of the gem?, answer: 478-carat | question: Where was the diamond mine found?, answer: African nation of Lesotho | question: Where was the diamond found?, answer: southern African nation of Lesotho. | question: How many carats was the stone?, answer: 478-carat