How much is the world's second-biggest diamond worth?

The world's second-biggest diamond is up for auction. It's expected to fetch $70 million.

The 1109-carat diamond - the size of a tennis ball - is scheduled to be auctioned next month by Sotheby's in London.

The diamond was discovered in November in Botswana in southern Africa.

The largest diamond is a 3,106-carat stone found in South Africa in 1905.

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