With consumers beginning to ask where their diamonds come form, prodding the industry to ensure that they are not indirectly financing civil wars, a conference of the World Diamond Council in Ramat Gan (Israel), has started working on ways to stop trade in "conflict diamonds," precious stones sold by factions in civil wars.

It isn't easy, they admit. Once they're out of the ground, diamonds look pretty much alike. Discussing the issues at Israel's diamond exchange, one of the world's top cutting and trading centres, members of the council decided on a new certification system. Up to now, certificates have stated the country where the gems were sold. The council is aiming for certificates that list the country of origin as well. Used together with lists of forbidden mines and regions, the system would cut into the conflict diamond trade.

In addition to an international chain of warranties, the council called on individual governments to pass legislation banning the import and export of undocumented diamonds. The council threatened to expel banks, insurance companies or shippers from industry guilds if they are caught dealing in conflict gems.

The diamond trade, worth about $ 6 billion a year, has been tarnished by disclosure that rebel groups in Sierra Leone and Angola have bought weapons through diamond sales and committed atrocities in their struggles against elected governments. Industry officials say that conflict diamonds account for only 4 per cent of their trade but fear that protests could damage their reputations.