Ngozi Okonjo-Iweala

Nigeria, with the oil sector, had the reputation of being corrupt and not managing its own public finances well. So what did we try to do? We introduced a fiscal rule that de-linked our budget from the oil price.

The price of diamonds can vary greatly depending on size, cut, color, and other factors, including whether they have a history. But because of the rarity of blue boron diamonds, they often fetch more money than gems of similar quality.

It is only when you watch the dense mass of thousands of ants, crowded together around the Hill, blackening the ground, that you begin to see the whole beast, and now you observe it thinking, planning, calculating. It is an intelligence, a kind of live computer, with crawling bits for its wits.