BBC Africa Analyst
A report indicating how Osama Bin Laden's al-Qaeda group has used the trade in precious gems to raise money and evade financial sanctions imposed on it has been produced by the British-based non-governmental organisation Global Witness.
Global Witness made its name exposing how the Angolan rebel movement, Unita, financed its war by smuggling diamonds.
Its latest report shows the intricate web of front companies and individuals that allowed al-Qaeda to earn money from the trade in African gold and gems and to move them around the world.
This report points to the problems al-Qaeda faced after 11 September, when a world-wide crackdown on the group's finances came into force.
But the group had carefully planned its move away from banks and into other assets.
As early as 1993, al-Qaeda had turned to gold, diamonds and other precious stones as a means of hiding its assets.
The group came to trade in the rare gemstone known as tanzanite - a beautiful blue stone, only found in one tiny area of Tanzania.
Attempts to control the trade are so inadequate - says Global Witness - they border on 'astonishing complacency'.
Similar allegations are made about diamonds, with stones sent from Sierra Leone to Liberia and then on to Belgium.
Failure to enforce tighter regulation, says Global Witness, will ensure that terrorists and organised crime, will continue to rely on the trade in precious stones.