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The second-biggest uncut diamond in history has been unearthed from a mine in Botswana.

The 1,758-carat diamond is about the size of a tennis ball.

The biggest diamond ever discovered is the 3,106-carat Cullinan, found in South Africa in 1905 - that was found before industrial mining began.

There has been a spate of large diamond finds in the last few years, which has been put down to new sorting machines that can process diamonds without breaking them.