The second biggest uncut diamond in history has been unearthed.

Diamond

Diamond

The huge 1,758-carat rock - which is larger than a tennis ball - weighs around 352g and was discovered by the Lucara Diamond Corp in a mine in Boswana.

Eira Thomas, the company's chief executive officer, said: ''Karowe has now produced two diamonds greater than 1,000 carats in just four years, affirming the coarse nature of the resource and the likelihood of recovering additional, large, high-quality diamonds in the future.''

It follows a second record discovery - the 1,109-carat Lesedi La Rona - in 2015, and the latest stone is second in size only to the 3,106-carat Cullinan Diamond.

The record holding diamond was found near Pretoria in South Africa 114 years ago.

Meanwhile, two of the polished gems from that stone - both the Great Star and Lesser Star of Africa - are featured in Britain's Crown Jewels.