15, 143 mins

Blood Diamond is so bleak and intense you will never look at a gem stone again without idly wondering how many lives it cost. The human price tag is nailed across the opening scene. A small convoy of whooping rebels rumble into a dusty fishing village in Sierra Leone. They hop out of jeeps sporting AK47s and designer sunglasses. Half are barely more than children. They swagger around the bamboo huts murdering the locals in glossy-up. The notional point of this exercise is to deter voters who have long since ceased to care. Survivors have their right arms chopped off at the elbow, or they are frog-marched to the diamond fields.

The politics of Edward Zwick’s campaigning thriller are as damning as the horror. Mercenaries like Leonardo DiCaprio’s unscrupulous arms dealer, Danny Archer, take cynical advantage of the civil war - and their white skins - to smuggle these illegal diamonds across the border to Liberia, and then launder them to unfussy dealers in the west. Zwick’s principled fury at the damage is utterly admirable. The hair-raising scenes of child soldiers being brainwashed by David Harewood’s rebel leader, Captain Poison, are filmed with Newsnight indignation.

What’s impossible to square is the ridiculous action movie Zwick pulls out of the carnage. Squashing the ghastly truth into a predictable mainstream entertainment diminishes the film’s punch. Zwick squanders the high ground for Hollywood romance and explosive thrills. DiCaprio delivers a wonderfully sour performance as the anti-heroic bastard, Archer. I haven’t seen an actor dodge so many bullets and bombs since the glory days of Arnold Schwarzenegger. Archer will stop at nothing to get his hands on a giant pink diamond discovered by a fisherman taken prisoner by the rebels.. But there is a generous streak of Indiana Jones about DiCaprio’s dashing adventurer. We know his heart is not quite as concrete as he thinks when Jennifer Connelly’s beautiful American journalist slides a guilty needle into it.

Djimon Hounsou’s terrified peasant Solomon realises the flawless stone he has found and hidden from the rebels might pay the way to his missing family. DiCaprio and his psychotic creditors see it as their chance to cash in their chips and escape Africa forever. The quest to recover the blood diamond from its hiding place rapidly turns into a sweaty chase movie complete with spectacular stunts, awesome sunsets, and helicopter shots of squalid slums lest we forget we’re in Africa.

Connelly’s shapely hack angles for the exclusive story that will expose the western dealers who oil this cycle of relentless and depressing violence. If the film wasn’t quite so self-righteous, simplistic, and sentimental it would be a far more potent story. But once again Africa is entirely indebted to a couple of white Hollywood stars who appear to have the only means of saving the country from itself.

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