World's largest existing diamond to be auctioned

'Lesedi la Rona', the largest gem-quality rough diamond in existence today, will be auctioned in London on June 29, as per the auction house Sotheby's on Wednesday. Believed to be around 2.5 to three billion years old, the tennis-ball sized 1,190-carat diamond is expected to sell for $70 million. The precious gem was excavated in Botswana in November 2015.
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