These are the miners who pull the world's most valuable stones from Sierra Leone's reddish ground and generally find themselves living in poverty as they ply their trade.

'I never knew how to weigh them, how to even use the scale,' said Ibrahim Jalloh, who has worked in the murky diamond mines for four years. Most miners know nothing more about diamonds than how to watch for their milky shine while shifting and shaking their sieves.

'If you go around to any of the mining sites right now and ask them how they determine the price, they'll tell you, 'well, we look at it and we think whether any like it have been sold in the past couple of weeks and we go for that price',' said Babar Turay, a manager with the Integrated Diamond Management Programme.

'They don't have the faintest idea what the price is.'

Ignorance and exploitation go hand in hand in these diamond fields, so the miners are being sent to a kind of diamond university, where they learn to fend for themselves against dealers and buyers who would otherwise cheat them.

The plight of the West African diamond miner has been pushed into public conscience with the release of the Leonardo DiCaprio film, Blood Diamond, showing enslaved diggers frantically searching for stones that helped fund their captors' war.

Although the industry has launched a major offensive to convince prospective diamond buyers that the gems no longer fuel bloody conflicts, it is here on the ground where changes are most needed.

Since diamonds were discovered in Sierra Leone in the 1930s, experts estimate about a billion carats have been harvested from the red soil of its eastern regions. In 2000, US$10 million was generated by diamonds exports. By 2004, that figure had grown to US$130 million.

Kono is the epicentre of Sierra Leone's diamond region, but there is no sign of wealth in the rough-and-tumble town. Kono was the major focus of the Revolutionary United Front rebels during the country's decade-long civil war; rivers changed their routes and buildings toppled as diggers tore through the town.

There is no running water or electricity. Sierra Leone routinely falls at the bottom of the United Nation's Human Development Index, with 70 per cent of the country's 6 million people living on less than a dollar a day.

Today, miners can only dig on licensed lands, which forces many Sierra Leoneans into partnership with the wealthy Lebanese diamond dealers, who can afford the US$40,000 licensing fee. The agreements are often signed with an X and closed with a handshake. Many of the miners are illiterate and would not understand a contract anyway.

The imbalanced financial arrangement means most miners feel compelled to sell their stones to their supporters, leaving them ripe for exploitation.

'The supporters have better knowledge and business management and with these weapons - the finances and the know-how - they always exploit the ordinary diggers and miners,' Mr Turay said.

He tells a fantastic story to illustrate the need for education among the miners.

A woman out planting potatoes lifted her bucket to return home and noticed a stone, which she pocketed and later presented to her pastor, wondering if it could be a diamond. He gave her 100,000 leones (HK$332) for it - and then sold the marble-sized stone to a diamond dealer for US$100,000. When the woman's chief got wind of it, he wanted his royalties, so he renegotiated and pushed the price up to US$350,000.

The dealer took the stone to be weighed, measured and classified by the Government Gold and Diamond Department in Freetown, where they determined the 156-carat stone was worth just shy of US$1 million. When it finally sold at auction to a Saudi gem merchant, it went for US$1.2 million.