The AP via CBC [www.cbc.ca] reports, and CNBC [cnbc.com] also reports, that the Lesedi La Rona [wikipedia.org] diamond is to be auctioned by Sotheby's in London in June. At 1111* or 1109 carats (around 222 g) it is the second-heaviest diamond discovered, after the Cullinan diamond [wikipedia.org] which had a mass of 3106.75 carats or 621.350 g. The stone was mined in Botswana last November and belongs to the Canada-based Lucara Diamond Corporation.
* according to an earlier report in the Wall Street Journal [wsj.com] (semi-paywalled)