They are beautiful and sparkling and precious, and they are everywhere -- as likely to be worn by rappers as by royalty. They are, we are told, "forever," the ultimate symbols of eternity and love. They are diamonds.

But behind the bling, bling lies the bang, bang -- an illicit and illegal diamond trade that funds everything from wars in Africa to al Qaeda operatives. These "conflict diamonds," which account for 1 to 4 percent of the overall diamond industry, are the subject of Edward Zwick's "Blood Diamond," which stars Leonardo DiCaprio as Danny Archer, a smuggler hot on the trail of a priceless stone that could change his life forever -- if it doesn't kill him first.

"Basically these diamonds have funded warlords to cause civil unrest and [led to] millions of people being murdered throughout Africa," DiCaprio said. "Child soldiers have to fight these wars, and [there are] millions of refugees."

For DiCaprio, the film was an education in corporate responsibility. Diamonds are a preferred method of terrorist finance, experts say, because of their intrinsic value and liquidity. By their very nature, they are also extremely difficult to trace.

"This movie is symbolic of what happens when we as consumers endorse a corporation and the way they do business by buying their products," DiCaprio said. "I could never have imagined that something that represents the symbol of love where we come from could have [caused] such devastation on a continent halfway around the world."

The film takes place in Sierra Leone during the late '90s, a time before most of the world's diamond traders (including South Africa's De Beers, which controls 60 percent of the overall market) ratified the Kimberley Process, a 2002 treaty designed to prevent conflict diamonds from making their way to consumers.

Nevertheless, conflict diamonds are still entering the American market, according to a 2006 report by the U.S. Government Accountability Office. "Blood Diamond" has had a "direct effect" on changing that, DiCaprio said proudly.

"There have been major improvements since the late '90s in the way that [diamond traders] conduct business," the actor said. "But the good thing about this movie is that the diamond industry is kind of already saying, 'All right, we're going to examine the way we do business again.' "

The diamond industry has long had a symbiotic relationship with Hollywood, each business contributing to the mythology of the other. With stars sashaying down red carpets wearing millions of dollars' worth of the precious gems, co-star Jennifer Connelly says the trick is not to avoid diamonds (she herself continues to wear them), but to be educated about their origins.

"Boycotting diamonds isn't necessarily the answer, but I think it would be fantastic if people decided to be more ethical in their consumerism," the Oscar-winning actress said. "And that can easily be done by asking questions when setting out to buy diamonds and diamond jewelry, asking jewelers to provide certificates that their diamonds are conflict-free."

But simply making sure that diamonds are conflict-free isn't enough for African-born co-star Djimon Hounsou, who urges people to take a more involved approach.

"It is unacceptable for us, the citizens of the world, to sit by and watch this take place," he said. "To do nothing is intolerable, and to do something is just not enough."

"Blood Diamond" opens Friday.

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