A model displays the 1,109 carat "Lesedi La Rona" diamond at Sotheby's in the Manhattan borough of New York, US, May 4, 2016. [Photo/Agencies]

NEW YORK - "Lesedi la Rona," the largest gem-quality rough diamond discovered in more than 100 years, will be auctioned in London next month and is expected to sell for $70 million, international auction house Sotheby's said on Wednesday.

Ahead of the auction on June 29, the 1,190-carat diamond, its name in Botswana's Tswana language translates as "Our Light", was on display at Sotheby's New York headquarters.

David Bennett, worldwide chairman of Sotheby's jewelry division, said the size of the Lesedi la Rona amazed experts.