The difference between dark and bright scenes with the Blood Diamond Blu-ray is like someone pressing the ‘HD’ button. For instance, soon after the noisy grimness of the opening scene I mentioned we get a shot of nasty thugs driving towards Vandy’s village that looks really quite superb. There's sensational detailing and sumptuously rich colouring in the green foliage around the jeep, not to mention stunning subtlety in the portrayal of the skin tones of the jeep's occupants and the dust cloud behind it. Plus there’s little if any grain and dot crawl. And remember, this is all happening on an image packed with motion. Superb stuff.

But of course, Blood Diamond is not a film comprising exclusively bright scenes. And every time a dark one arrives, the accompanying noise can be bad enough to actually disengage you from the film.

Plus there are a couple of other negatives. First, I felt like the colours sometimes bleached out a little during extremely bright scenes. Second, rather freakily the picture seems out of focus at the top and especially bottom during certain shots. It’s possible this is some curious filter or anamorphic effect created during filming, as the subtitles seem perfectly in focus even when the picture behind them is not. Then again, the subtitles may be superimposed after the film’s been copied from the master… Oh, alright. Basically, I haven’t got a clue what’s going on. But I certainly do know that it's bloody annoying. Overall, I don’t think there’s any other HD title I’ve seen that’s given me so many picture highs and lows. Which is nice-reviewer speak for 'it’s a royal mess'.

I should add before concluding here, by the way, that the transfer is a 2.4:1 aspect ratio, encoded in 1080p/24.

Once you’ve got your home cinema system set suitably loud, however, the soundstage turns out to be surprisingly good. Not because it does anything particularly clever in terms of subtle effects, but because it knows how to burst into life when required. As the government troops raid the R.U.F. diamond mine, for instance, the explosions of the grenades shake the room, with prodigious amounts of bass erupting from your subwoofer while your main speakers suddenly seem to have been turned to ‘11’. (Sorry about the This Is Spinal Tap reference there, but sometimes it just has to be done.) Yet as a sign of how carefully the whole thing has been mixed, you can still clearly make out every individual bullet and every word that’s said even when a grenade feels like it’s just gone off right under your feet. Mind you, the dialogue clarity has the unfortunate side effect of revealing what we’ll charitably call one or two interesting ‘dialects’ to Leonardo DiCaprio’s African accent.

Having praised the Dolby Digital mix so highly, I can now reveal that this mix isn’t even the star of the audio show. That’s actually the PCM 5.1 mix, with its uncompressed HD audio. This delivers even greater bass extension, if it’s possible, than the Dolby Digital one, and generally just sounds that bit richer.

Actually, although this might sound a bit daft, for me the Blood Diamond soundtrack is almost too well engineered. For it fits into that sense I mentioned earlier of this being too much of a Hollywood production, with all the high production values detracting from the ‘grit’ of the subject matter. But hey, that’s just a personal view related to my response to the film. As a serious tester of your sound system, Blood Diamond is, surprisingly, mustard.

The Extra Features menu is particularly nightmarish, presenting you as it does with a truly terrifying face full of nothing but text...

Occasionally the Blu-ray's pictures sparkle technically, too.

It’s just a pity that these periods of sparkle are joined by just as many moments of messiness.