Yup, the diffuse MUST be black for a perfect mirror (a perfect mirror has no colour of it's own, it just reflects everything back).

Although it seems confusing, this exactly "mirrors" the physical world. All surfaces absorb some colours from the light hitting them and reflect the remainder. That's what gives them their colour, the bit that gets reflected.
Most surfaces scatter that reflected light, since they aren't very smooth (at a microscopic level), so you don'y see much in the way of reflected images in them. However, mirrors are designed to be as smooth as possible, so tend to reflect light at the same angle, thus producing images.
I am being a bit simplistic here, but am trying to make the concept clearer to those with less knowledge of light physics than me, and I'd be the 1st to admit that my understanding is only surface-deep.

Anyway, what all this means is that setting the diffuse (and ambient, for that matter) colours on the mirror to black give you better reflections.
However, if you want to get a reflection in (eg) a highly polished bronze armour breast-plate, then set the diffuse to a bronze colour..:-))

(That's enough for now. I'll shut up.)

Cheers,
Diolma

Message edited on: 09/16/2005 16:10