A 1,111 carat diamond is biggest to be unearthed in the last century

A 1,111 carat gem-quality diamond, second in size only to the Cullinan diamond cut into the British Crown jewels, has been unearthed by Lucara Diamond in Botswana.

The Type-IIa stone, just smaller than a tennis ball, is the largest diamond discovery for more than 100 years, according to Vancouver-based Lucara. It was recovered by machines at the south lobe of Karowe mine in central Botswana, the company said.

"The significance of the recovery of a gem-quality stone larger than 1,000 carats, the largest for more than a century and the continued recovery of high-quality stones from the south lobe, cannot be overstated," said William Lamb, CEO of Lucara.

"It is almost impossible to estimate a value for such an extraordinary stone given that valuation is dependent on colour, clarity, cutting and polishing characteristics," said Edward Sterck, a London-based analyst.