A BBC investigation in Zimbabwe has uncovered evidence that senior people around President Robert Mugabe are benefiting from the sale of illegal diamonds. World Affairs Editor John Simpson has just returned from a visit to Marange, in eastern Zimbabwe, which contains the largest known concentration of diamonds in the world.
Some 68 illegal diamond diggers were buried in a mass grave
Until six months ago the Marange diamond fields were occupied by hundreds of illegal local diggers.
The diamonds were easy to find. They either lay on the surface or just a few feet below.
The diggers sold them to dealers in nearby town of Mutare, who smuggled them out of the country.
Then on 31 October, we were told, the government moved in.
Helicopter gunships, soldiers and police were sent to attack the illegal diggers.
At least 150 of them were killed. According to survivors we spoke to, some of them were set on by police dogs and torn apart.
Senior sources in the capital, Harare, insisted that an operation on this scale could only have been authorised by President Robert Mugabe himself.
Now the diamond fields at Marange are under the control of the army, and the roads around it are guarded by police road-blocks.
It proved to be very hard for us to film the diamond fields for the BBC, though in the end we managed it.
Yet, as it turned out, the purpose of the operation was not to take over the diamond diggings in order to provide revenue for Zimbabwe's almost empty treasury.
Diamonds are still being dug out at Marange, but reliable sources in Zimbabwe insist that they are not appearing on the legal market.
Instead, we were told, they are still being smuggled out of the country and sold illegally.
So who are the beneficiaries?
In Harare we spoke to a former judge, who was once President Mugabe's top civil servant and played a key role in the Lancaster House negotiations in 1980 which brought about Zimbabwe's independence.
Justice George Smith retired from the bench in 2003, and nowadays he is a consultant to Zimbabwe's diamond industry.
In the current climate in Zimbabwe, it is dangerous even for a man as distinguished as Justice Smith to name names.
But when I asked him if he was talking about people right at the top, he replied: "Very much so."
Zimbabwe has great mineral riches, yet it has been driven almost to economic collapse.
One hundred trillion Zimbabwe dollars are now worth $3 (£2).
Yet Robert Mugabe's closest supporters thrive as a result of illegal diamonds.
Not surprisingly, people in Zimbabwe call them "blood diamonds".