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Ths Cullinan Mine: In this enormous hole, nine meters below the surface, they found what had been the world's biggest diamond until now. - 


Scott Jagow: In 1905, South African miners found a diamond that weighed 3,106 carats. It's been the world's biggest diamond for more than a century. But we're getting reports out of South Africa that a much bigger diamond was just discovered. Gretchen Wilson is in Johannesburg.

Gretchen Wilson: The diamond is reportedly light green and the size of a soccer ball. It's about 7,000 carats, or well over a pound.

That's more than two times the weight of the previous record-holder, the Cullinan Diamond. That was discovered in South Africa more than 100 years ago. It was broken into individual jewels, including the Great Star of Africa, valued at $400 million.

Diamond experts in South Africa say the new gem still needs to be assessed. If it's of similar quality, it's sure to start furious bidding from buyers around the world.

As we speak, the behemoth stone is being transported to Johannesburg under tight security. It'll be placed in a vault as company officials take a deep breath and decide what to do next.

In Johannesburg, I'm Gretchen Wilson for Marketplace.