Researchers from the University of Ghent and the Diamond High Council in Belgium were able to figure out the chemical "fingerprint" of a diamond after making a tiny hole in it with a laser beam.

The print helps them identify the mine from which it came because each precious stone has a chemical composition specific to an individual mine.

Diamonds fund bloodshed

Rebel groups in countries such as Sierra Leone, Angola and the Democratic Republic of Congo have used conflict, or blood diamonds, to finance wars and commit human rights abuses.

It will take years to build up a global picture of the illegal diamond trade ... experts

About 70 diamond producing countries have agreed to curb the trade and have a July 31 deadline to meet monitoring requirements or face a trading ban.

The Diamond High Council, based in the world's largest diamond distribution center of Antwerp, said in a statement that the researchers would need years to get a global picture as they had to analyze samples from every operational mine in the world.

So far they have analyzed diamonds from Russia, Botswana, South Africa and Canada, it said.

To complicate matters, many diamonds are often found in river beds, hundreds of kilometers from where they originated.

Last month the U.N. Security Council decided to drop diamond sanctions against Sierra Leone, first introduced in July 2000, although the ban on exports of the gem from Liberia remains intact.

The research results will be published shortly in the Journal of Analytical Atomic Spectometry, the council said.