LONDON (AP) — A London auctioneer says a diamond the size of a tennis ball that is the largest discovered in more than a century could sell for more than $70 million.

Sotheby's says it will offer the Lesedi la Rona diamond in London on June 29.

The diamond was unearthed in November in Botswana at a mine owned by Canada's Lucara Diamond Corporation. It measured 1,109 carats, the second-largest gem-quality rough diamond ever discovered.

Its name means "our light" in the Tswana language.

The auctioneer said Wednesday that the rough gemstone could yield the largest top-quality diamond ever cut and polished.

The largest diamond ever found was the 3,106-carat Cullinan diamond, unearthed in South Africa in 1905. It was cut into nine pieces that form part of the U.K. Crown Jewels.