The boss of a small diamond company says he is at a "loss for words" after several large diamonds, including the largest in more than a century, were recovered in Botswana.

Canada-based Lucara Diamond said the 1,111-carat stone was found on the south lobe of its Karowe mine in the southern African nation, declaring it the world's second-biggest gem-quality diamond ever recovered after the Cullinan diamond which features in the Crown Jewels.

The company said that it was yet to be fully examined and processed, meaning it was impossible to put any kind of value on it.

It will be determined by its color and clarity and how it is cut.

After Lucara announced the gem's discovery, it confirmed 24-hours later that two further stones - the largest being an estimated 813 carats - had been found as well at the same mine.

The focus, however, was on the Type IIa diamond - which measured 65 mm by 56 mm by 40 mm.

William Lamb, company's chief executive, said: "This historic diamond recovery puts Lucara and the Karowe mine amongst a select number of truly exceptional diamond producers.

"Our focus on mining the south lobe, which is delivering value beyond expectation, has been perfectly timed with the commissioning of our recent plant modifications, enabling the recovery of these large, high quality exceptional diamonds."

The Cullinan diamond was a 3,106-carat stone found in the Premier mine in South Africa in 1905.

It was cut into several polished gems to form the Great Star of Africa and Lesser Star of Africa.

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