Sierra Leone in 1999 is rich with diamonds and lousy with men who use them to get fat and wage war. As outlined by Blood Diamond, innocents are rounded up and forced to sift for diamonds that, when found, are used to buy weapons to prosecute civil war. These "conflict diamonds" are bought by conglomerates that then either mix them with non-conflict stones and sell them in legitimate jewelry stores around the world or warehouse them to keep them from flooding the market and driving the price of the ostensibly rare item down.
Danny Archer (Leonardo DiCaprio) is the middleman in the scheme, the weapons runner who trades arms for stones then sells them to the diamond big boys in London. Solomon Vandy (Djimon Hounsou) is a forced-labor Sierra Leonean who finds a dandy of a rock and hides it before being arrested following a government raid on the rebel camp.
Archer gets thrown in the clink with Solomon and pieces together Solomon's gem tale. Archer pulls strings to get the two released and proceeds to push Solomon into guiding him across the war-torn country to get the diamond. Along the way, they pick up a companion in Maddy Bowen (Jennifer Connelly), an American journalist looking to expose the diamond industry's profiteering.
As a professional, Maddy wants Archer on record with what he knows about diamond-trafficking; as a woman, she wants to know if Archer has any interests that aren't self-serving. Early on, Archer mostly wants to know if Maddy has anything he can use to further his cause. The chemistry between Connelly and DiCaprio is off the charts. (Though, to be fair, so is Connelly's chemistry with the jungle, her camera, her typewriter, the setting sun, a table ... )
Blood Diamond finds DiCaprio again doing stellar work. His South Africa-inflected accent is full of grunts and yammers; it sounds effortless. As scripted, Archer's path to enlightenment is a tad too labored, but the actor overcomes it by making you believe both the rogue and the gent.
One of the jokes in the film is that if oil were discovered in Sierra Leone, then there'd really be problems. Title notwithstanding, diamonds aren't the story in Blood Diamond. As one character says: "T.I.A." -- or "This Is Africa," which roughly equals "Forget it, Jake. It's Chinatown."
The war of ideals between the two sides is a smoke screen for people just getting theirs; it's a war with no policies, only consequences. The diamond at the center of the plot is a 100-carat MacGuffin, a stand-in for whatever it is -- precious stones, oil, rubber, God, the Almighty Dollar -- that drives men to atrocity. The widening gyre, things fall apart, the blood-dimmed tide, etc.; the madness that leads to "an entire continent made homeless." This is the main thrust of Blood Diamond, and in this regard, it's a brilliant film.
Implicit is the indictment of Western consumer indifference. The movie mostly avoids 2 a.m.-infomercial homilies in its insistence that Westerners are operating under a false perception of reality: Diamonds aren't forever; civil wars are.