User blog comment:Sorairo/On the Topic of Dust: Explanation?/@comment-11188061-20130813013745

I think the the notion 'if the robots glow Red they must be using Red dust' is a bit foolish. We know that a simple red-colored lens or filter is all that's needed to make a white/yellow light look red from the outside, and hence we definitely cannot decide what type of Dust that's powering the droids just from the fact that 'it glows red' until we see the actual process itself. The red color design may just be a form of warning to potential thieves or sabotagers like Blake/Adam.

Also, we cannot say decisively that the Beowolves are created from Red Dust. We may speculate that Cresent Rose was powered by Red Dust, and hence when she slices through the Beowolves it leaves a trail of red-colored, petal-like imprints as they dissolve into nothingness. This speculation is further supported by the fact that at the start of Red Trailer we can clearly see a similar trail of red petal imprints flushing out from Ruby's cloak, though exactly what it signifies is anyone's guess.

One may even say that the Beowolves are not related to the Dusts in any way at all, since they are creatures of darkness and hence were composed of an entirely different matter.

Out of all your speculations the Green one is the most shaky - in fact I don't think we've ever seen Green Dust in action before - but the otherwise are very well theorized. I would guess that Blue is in fact water element Dust (or something that's the opposite of Red) and thus when the two types collide with each other it caused a rather explosive reaction.

Grey may be a form of common fuel that's used to power up machinery. I actually think that it's more plausible to speculate that Grey Dusts were used as batteries/power source to power up the metal droids and guardians we've seen so far, and if we were to use your logic, it would be because they were all colored grey lol.