The largest diamond found in more than a century has been unearthed at a mine in Botswana, and the country's president showed off the fist-sized stone to the world on August 22. The Botswana government says the huge 2,492-carat diamond 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 about half a kilogram and Masisi was one of the first to hold it. Masisi said: "I am lucky to have seen it in my time." He said "wow" before calling government officials over to take a closer look. Officials said it was too early to value the stone or decide 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. Naseem Lahri, Botswana managing director for Lucara, the Canadian mining company that found the diamond, added: "I am very proud. It is a product of Botswana." Lucara said in a statement that it recovered the "exceptional" rough diamond from its Karowe Mine in central Botswana. Lucara said it was a "high-quality" stone and was found intact. It was located using X-ray technology designed to find large, high-value diamonds. The weight would make it the largest diamond found in 119 years and the second-largest ever dug out of a mine after the Cullinan Diamond that was discovered in South Africa in 1905. The famous Cullinan was 3,106 carats and was cut into gems, some of which form part of the British Crown Jewels. Botswana, a country of 2.6 million people in southern Africa, is the second-biggest producer of natural diamonds behind Russia and has unearthed all of the world's biggest stones in recent years.