The largest diamond found in more than a century has been unearthed at a mine in Botswana. The country's president showed off the fist-sized stone to the world at a viewing ceremony Thursday. The Botswana government says the huge 2,492-carat stone is the second-biggest ever discovered in a mine. It's the biggest diamond found since 1905. The diamond was presented to the world at the office of Botswana President Mokgweetsi Masisi. It weighs approximately half a kilogram. Officials said it was too early to value it or decided how it would be sold. Another smaller diamond from the same mine in Botswana was sold for $63 million in 2016, a record for a rough gem.