Consumers in the market for a diamond may want to consider the politics of their purchase, after Britain's call for an end to trade in all so-called "blood" diamonds.

"Blood" diamonds is the term used for gems that come from war zones such as Sierra Leone and Angola. It's thought the money raised in their sales is used to finance arms purchases.

British Foreign Secretary Robin Cook outlined his proposal for a ban on the precious rocks in London's Parliament this week.

"We are exploring with partners in the Security Council our proposal for a UN resolution banning the trade in diamonds from Sierra Leone, except where they are certified as legitimate by the government of Sierra Leone," he said.

Cook says the illicit trade in diamonds is what keeps the war going in the troubled African nation. The Foreign Secretary believes halting the trade would reduce the rebels' ability to wage war.

But diamond traders in the world's diamond capital of Antwerp, Belgium, say the origin of most of the diamonds that pass thorough their hands remains a mystery. They say they can't be expected to be sure about which stones come from where.

They also point out that a similar 1998 UN Security Council resolution aimed at banning all sales of Angolan diamonds without certificates of origin has so far shown little success in stopping the flow of arms to Angolan rebels.