The largest diamond in more than a century has been discovered in Botswana– and experts say the gargantuan gem could be worth more than $100 million.

The president of Botswana, the African nation where the precious stone was unearthed by miners, showed off the fist-sized diamond – which at 2,492 carats weighs about a pound – at a viewing ceremony this week.

Officials said it was too early to value the stone or decide how it would be sold. But sources close to Lucara, the Canadian mining company that found the diamond in its Karowe Mine, estimated it could be worth more than $40 million.

Some industry insiders said that looked like a conservative number, based on the glittery rock’s astounding size.

Top diamond expert Fred Cuellar noted that in 2016 a smaller diamond from the same mine in Botswana was sold for $63 million.

Cuellar said diamonds are priced like houses: “What is a similar house sold for in the neighborhood?” If his suspicions are correct, he said the diamond is worth between $100 million and $160 million.

The diamond likely contains one “breathtaking” stone inside along with six or seven other stones, Cuellar told The Post.