Until he got to Africa, Leonardo DiCaprio admits, his exposure to the conflicts surrounding diamond mining was limited.

“I was like anybody else, I’d heard whispers, but it wasn’t until I got to Africa and heard firsthand accounts that I began to realize the immense impact,” he recalls.

He maintains it wasn’t the consciousness-raising aspect of Ed Zwick’s movie that initially attracted him, but, rather, the character of Danny Archer, a loutish, swaggering South African soldier of fortune engaged in the bloody business of smuggling raw diamonds out of the country.

“After Archer is touched by the plight of a desperate fisherman (Djimon Hounsou) and gets his ethics challenged by a passionate reporter (Jennifer Connelly), he begins to think about interests larger than his own.

“It was such a powerful character,” DiCaprio says of the role, which required him to plunge into mastering tricky South African patois. “But a film has to be entertaining, it has to convey a message without people feeling that they are being preached to.”

Once on location, he “spent a lot of time with the locals, drinking beers with them, hearing their stories” as well as running exercises with soldiers to prepare for the film’s intense action scenes.

“He immersed himself completely in the character,” observes Zwick, who traveled overseas on his last pic as well, the Tom Cruise starrer “The Last Samurai.” “A lot of what you see onscreen are little things Leo came up with, based on what he had learned about the dialect or the local idioms.”

Set against the chaos that enveloped Sierra Leone in the 1990s, when countless children were conscripted as soldiers in a civil war, the graphic storytelling involved “weeks of squibs going off and diving behind cars,” as DiCaprio remembers it. Up to their hips in muck, he and Hounsou sometimes passed the time chatting with each other “like two weird women, talking about cafes in Paris and where we’d like to be, sipping lattes and eating pastries.”

At times, the actor recollects, “It was an uncomfortable situation, to be in Africa portraying this man who is taking advantage of the poverty of others.”

But after six months on location, he says, “What I was left with was really feeling the power of the human spirit there. These people have been through so much, but literally they were still dancing in the streets. The joy and energy and happiness they exuded, it really made me come back home and not want to listen to anybody’s problems.”

As to whether acclaim for his performances in both “Blood Diamond” and “The Departed” could mean he competes against himself come awards time, DiCaprio replies: “That’s for everyone else to decide. We just make these movies and put them out there, and you never know what’s going to happen.”

Favorite film of the past five years: “An Inconvenient Truth”

Actor who impressed you greatly after working together: “Djimon Hounsou. The intensity and energy that you get from him as an actor is amazing, and I got to play off that every day.”