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.”

Lucara said in a statement Wednesday 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.

“We are ecstatic about the recovery of this extraordinary 2,492-carat diamond,” Lucara President and CEO William Lamb said in a statement.

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.

A bigger, less pure black diamond was discovered in Brazil in the late 1800s, but it was found above ground and was believed to have been part of a meteorite.

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. The Karowe Mine has produced four other diamonds over 1,000 carats in the last decade.

Before this discovery, the Sewelo diamond, which was found at the Karowe Mine in 2019, was recognized as the second-biggest mined diamond in the world at 1,758 carats. It was bought by French fashion house Louis Vuitton for an undisclosed amount.

The 1,111-carat Lesedi La Rona diamond, also from Botswana's Karowe Mine, was bought by a British jeweller for $53 million in 2017. Another diamond from Karowe, The Constellation, was sold for the record $63 million.

Diamonds are formed when carbon atoms are squeezed together under high pressure deep underground. Scientists say most diamonds are at least a billion years old and some of them more than 3 billion years old.