Consider the nation of Sierra Leone, in West Africa. They have a bounty of diamonds. And they're at the heart of a civil war: over the last decade, the various factions have killed at least 75,000 people, and they've maimed and crippled thousands more. The fighting has driven millions of citizens from their homes.

Earlier this year, the warring sides began to negotiate peace. But the main rebel group, the Revolutionary United Front (RUF), refuses to give up control over their most valuable weapon: they run the country's richest diamond mines.

Sierra Leone is blessed with fertile soil…but its chief crop isn't cassava or groundnuts. Millions of years ago, deposits of compressed carbon formed here — miles beneath the earth. Then, subterranean volcanoes erupted, shooting diamonds to the surface. Today, you can find them sprinkled in the sand and gravel of Sierra Leone's alluvial plains.

On a hot and humid afternoon, a canoe dug out of a hollow tree trunk floats in the Sewa River. A rusty generator hums on the bank. And, unseen, below the surface, a man stands on the river bottom — scraping gravel into a bucket.

The humming generator is the machine that gives him air to breathe.

Sensei Condo says that the man beneath the river is a diamond miner like himself. He explains, "The machine has an airline directly into the river. He breathes just the way I am breathing, sitting in the river."

The man scrapes the river gravel into a bucket attached to a rope, which he pulls on twice when he wants it lifted out.

Sierra Leone has thousands of subsistence miners like these men, scraping a living out of the ground. But for years, diamonds mined by the rebels have made the really big money — an estimated 250 to 300 million dollars a year. That money has brought war and mayhem instead of development.