A massive diamond, believed to be the largest discovered in over a century, has been unearthed in Botswana. Weighing 2,492 carats—roughly the size of a fist and about a pound in weight—the gem was exhibited by the nation’s president during a viewing ceremony this week.

While the exact value of the stone is yet to be determined, sources close to Lucara, the Canadian company that mined it from the Karowe Mine, suggest it could be worth over $40 million, with some experts estimating it may exceed $100 million, according to the New York Post.

Industry experts suggest that the estimated value of the newly discovered diamond in Botswana might be conservative given its immense size. Renowned diamond expert Fred Cuellar pointed out that in 2016, a smaller diamond from the same mine was sold for $63 million.

Cuellar likened diamond pricing to real estate, where value is determined by comparing sales of similar properties. He estimated that the newly discovered diamond in Botswana could be worth between $100 million and $160 million.

He also speculated that the massive gem likely holds one “breathtaking” stone inside, along with six or seven other valuable stones.

Before this week’s discovery, the Sewelo diamond also found at Botswana’s Karowe Mine held the title of the world’s second-largest diamond at 1,758 carats.

It was purchased by Louis Vuitton for an undisclosed amount.

The largest diamond ever found remains the Cullinan Diamond, a 3,106-carat gem unearthed in South Africa in 1905.

Valued at $400 million at the time, the Cullinan was cut into multiple gems, some of which are now part of the British Crown Jewels.

The newly discovered diamond, still unnamed, was officially unveiled this week at the office of Botswana President Mokgweetsi Masisi. The president was among the first to hold the massive gem during its presentation.

“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.

The Karowe Mine has yielded four other diamonds exceeding 1,000 carats in the past decade. Lucara, the Canadian company that operates the mine, revealed that this latest historic diamond was discovered using advanced X-ray technology.