GABORONE, Botswana  — 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 at a viewing ceremony Thursday.

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 as-yet-unnamed diamond was presented to the world at the office of Botswana President Mokgweetsi Masisi. It weighs approximately half a kilogram and Masisi was one of the first to get to hold it.

“It is overwhelming,” Masisi said. “I am lucky to have seen it in my time.” He gasped and said “wow” before calling senior 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.

“This is history in the making,” said Naseem Lahri, Botswana managing director for Lucara Diamond Corp., the Canadian mining company that found the diamond. “I am very proud. It is a product of Botswana.”