CANADA- The second-biggest uncut diamond in history has been unearthed from a mine in Botswana by a Canadian mining company.

Lucara Diamond Corp discovered the 1,758-carat diamond, which is larger than a tennis ball and weighs close to 352g, just three years after making a separate record discovery in 2015.

The company struggled to sell the previouslydiscovered 1,109-carat “Lesedi La Rona” after it failed to meet its undisclosed reserve price at a June 2016 auction.

It was eventually bought for $53m (£41.1m) by British dealer Graff Diamonds nearly two years later.

Following the latest find, Lucara’s shares rose as much as 11.4% to the highest in more than two months before closing up 6.3%.

The stone is second in size only to the famed 3,106-carat Cullinan Diamond, which was found near Pretoria in South Africa in 1905.

Two of the polished gems cut from the Cullinan - the Great Star of Africa and the Lesser Star of Africa - feature in the Crown Jewels of Britain.

A close up of a wine glass: Lucara says it has found a number of high-value diamonds in recent years. File pic