One of the world's 20 largest diamonds, discovered by a pastor from Sierra Leone, is about to be auctioned in Antwerp, Belgium.

Pastor Emmanuel Momoh, 39, unearthed the 709.41-carat diamond in the Kono district of Sierra Leone. It is the second largest diamond ever found in that country.

Momoh has travelled to Belgium with the diamond to meet sales agents, auction houses and potential buyers.

The diamond was auctioned in Freetown in May, but the highest bid of $7.7 million was turned down.

Momoh told Agence France Presse: 'I want my diamond to be sold abroad so I can get the best price to enable many people to benefit from the proceeds.

'I'm expecting not less than $50 million from the diamond'.

Momoh is one of hundreds of artisanal miners in Kono, Sierra Leone's key mining district. On finding it, he handed it over to the government but remains its chief owner. The government's stake in the sale of the diamond will be used to fund development projects nationwide, according to Forbes.

Kono was at the centre of the trade in 'blood diamonds' between 1991 and 2002. The trade helped to fuel a decade-long civil war as rebel groups used gems to pay for weapons.

A year after the conflict ended in 2002, the Kimberley Process international certification scheme was created to keep so-called conflict diamonds out of the market and lay down export conditions applying to the agreement's 75 signatories.