A 1,111 carat diamond has been recovered in Botswana by the mining company Lucara. The Type IIa diamond is the largest discovered in more than a century and second in size only to the diamond that was used to make the British crown jewels, according to Bloomberg. The diamond is almost as big as a tennis ball.

“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,” Lucara CEO William Lamb said in a release.

An analyst at BMO CApital Markets said the value of such a massive stone was “impossible to estimate” because the value is dependent on the color, clarity, and cutting of the gem. A 341.9 carat diamond sold for $20.6 million in July.