The precious stones are at the heart of former Liberian leader Charles Taylor's war crimes trial in The Hague, who allegedly used them to buy weapons for Sierra Leone's Revolutionary United Front (RUF).
Taylor denies ever handling or possessing the diamonds but is alleged to have given one as a gift to Naomi Campbell, the supermodel, following a charity dinner hosted by Nelson Mandela in 1997.
Giving evidence at the trial, Campbell admitted she was given a pouch of "small, dirty looking stones" by two men in the middle of the night following the dinner.
Conflict diamonds are defined by the United Nations as "diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognised governments, and are used to fund military action in opposition to those governments, or in contravention of the decisions of the Security Council."
Under a UN resolution, an international certification scheme for rough diamonds was set up in 2003 to halt the trading of blood diamonds, in an effort to ensure they could not be used to finance conflict.
As a result the Kimberley Process, which controls rough diamond production and trade, came into being and is now in action in 75 countries which account for 99.8 per cent of the world's rough diamonds.
Through the scheme – named after the South African city where the agreement was reached – all diamonds traded by member countries are certified so that buyers can be sure they have not contributed to atrocities.
There is no international law on the trading of blood diamonds but countries who have signed up to the Kimberley Process are prevented from importing or exporting them through domestic laws.
Blood diamonds are indistinguishable from ordinary rough diamonds, and individual jewellers are not certified by the Kimberley process, but buyers are advised only to use businesses who can guarantee that their diamonds are conflict-free and explain where they are sourced from.
However, the Kimberley Process was too late to stop the alleged use by Taylor of the stones to arm and control the RUF, a rebel force responsible for widespread attacks in Sierra Leone.
Taylor allegedly used blood diamonds from the RUF to buy weapons which he is said to have shipped from Burkina Faso to the Sierra Leone junta at the Magburaka airfield in October 1997.