The Sierra Leonean pastor whose workers found one of the world’s largest rough diamonds has pledged to build a new school and bridge in the village where it was found.

Pastor Emmanuel Momoh brought the 709-carat precious stone, found in the eastern Kono district, to the capital, Freetown, last week.

President Ernest Bai Koroma said Sierra Leoneans should benefit from the discovery and said it will be auctioned next month.

It’s hard to say what price it will fetch, but last May, diamond-mining firm Lucara sold a 813-carat stone for $63m (£51m) at a closed auction in London.

Pastor Momoh told the BBC’s Umaru Fofana what he hopes to do with his share of the money:

I have an action plan. I have to give my tithes. I promised God. I know that God still has a plan for me.

After giving my tithes, the village where we got the diamond, we have to make a bridge, we have to build a school, we have to improve the lives of the people.”