A Canadian mining company has found what's thought to be the second largest diamond ever in Botswana, measuring a whopping 1,111 carats — almost as big as a tennis ball.

TSX-listed and Vancouver-based Lucara said in a release late Wednesday it found the record-setting stone on the south lobe of the company's Karowe Mine in Botswana. It was recovered on Monday.

It's described as "gem quality, Type IIa," and its dimensions are 65 by 56 by 40 millimetres. One carat is equal to a fifth of a gram, so Lucara's 1,111-carat diamond weighs 222 grams.

That's the biggest gem-quality diamond discovered since the famed Cullinan measuring more than 3,000 carats was found in South Africa in 1905. The Cullinan was subsequently cut into smaller pieces, with the two largest portions incorporated into Britain's Crown Jewels.

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

There's every indication the company has tapped into the motherlode of large diamonds in its mine.

On Thursday, Lucara announced it had found two more large diamonds, one measuring 813 carats — the sixth largest ever recovered — and another measuring 374 carats in the same vein.

Diamonds measuring more than 100 carats are rare. The company knows it has a crown jewel of its own on its hands, which is why Lucara is in no hurry to sell it.

"I'm already getting emails saying, 'Is the stone for sale?'" Lamb said in a conference call with analysts to discuss the find.

"We're not desperate to sell it," he said, adding that the company will sell it at some point, but only after it has figured out how to maximize the diamond's value.