The largest gem-quality diamond discovered in more than a century was on public display recently in New York, reports VOA. The three-billion-year-old crystal, mined in Botswana last year, is about the size of a tennis ball. The diamond will be auctioned in London in the end of June and is expected to sell for at least $70m.

The stone was discovered by Lucara Diamond Corp. Below is an edited statement the company put out last year after the discovery:

Lucara Diamond Corp. is pleased to announce the recovery of a 1,111 carat gem quality, Type IIa diamond.

The magnificent stone, which originated from the south lobe of Lucara’s Karowe Mine, is the world’s second largest gem quality diamond ever recovered and the largest ever to be recovered through a modern processing facility. The stone was recovered by the newly installed large diamond recovery XRT machines. The stone measures 65mm x 56mm x 40mm in size and is the largest ever to be recovered in Botswana.

William Lamb, president and CEO, commented, “This historic diamond recovery puts Lucara and the Karowe mine amongst a select number of truly exceptional diamond producers. 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. 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.”