The diamond industry and Hollywood are involved in an increasingly heated spat over a forthcoming movie highlighting the gems' historical link to wars in Africa.
In a strike against what it fears will be a barrage of bad publicity, the industry has launched a campaign to tell people that more than 99 per cent of all diamonds are "conflict free". The campaign is co-ordinated by the World Diamond Council (WDC), a trade body that represents diamond producers such as De Beers.
The campaign has been launched ahead of the release of The Blood Diamond, a film starring Leonardo DiCaprio and Jennifer Connelly, due to be released in January. The movie is set against the background of the civil war in Sierra Leone that was partly fuelled by the trade in uncut diamonds.
The council wrote to the film's director and producer, Edward Zwick, demanding that the movie reflect what it said had been a transformation of the diamond industry. It said a scheme known as the Kimberly Process (KP) had established a system to authenticate diamonds not linked to wars.
"It would be a great pity if a movie as important as the one you are now producing told only a part of the story and suggested that the situation in Sierra Leone today and, indeed, in other diamond-producing countries had remained unchanged," the council wrote.
Mr Zwick responded in an interview with the entertainment website Eonline.com: "We're aware of the KP. The movie details the events of 1999 and our facts are in order. We're not negotiating with anyone as to the content of our movie."
Diamond campaigners say there is still concern about the trade despite the introduction of the KP. Amnesty International said: "One of the major criticisms [we] and other NGOs have made of the KP scheme is that there are inadequate checks on the diamond industry throughout the production and distribution process to verify industry compliance. This creates loopholes allowing illicit diamonds to enter the trade."
Corinna Gilfillan, a campaigner with the group Global Witness, said: "It's definitely true that there are less wars caused by diamonds than there were 10 years ago but there is still a long way to go."
The extent of the diamond industry's angst was revealed last year when Jonathan Oppenheimer, a director of De Beers, warned a trade convention in South Africa about the film, saying: "Can you imagine its impact on the Christmas-buying audience in America?"