Gaborone: A young man, just months into his apprenticeship at a mine uncovered the ‘diamond of the century’ which is now set to be auctioned for a record £50 million, reports DailyMail.

Tiroyaone Mathaba, 27, said he ‘wanted to scream’ when he found the tennis-ball sized diamond in the Karowe mine in Botswana.

It is the biggest find since 1905, when a 3,106.75-carat rough gem was uncovered in a South African mine and cut into nine diamonds – eight of which now form part of the Crown Jewels.

Named ‘Lesedi la Rona’, the diamond has been described as ‘find of a lifetime’ and its sale at Sotheby’s on June 29 is expected to smash the world record for the most expensive diamond ever sold at auction.

The Lesedi la Rona was uncovered by Mr. Mathaba last November, while he was on probation as a trainee at the Lucara Diamond Corp at its Karowe mine.

Mr. Mathaba spotted the diamond, which upon first glance appeared nothing more than a stone. However on closer inspection he realized it was exceptionally valuable.