Blue and yellow is how white light is made. A phosphor coating fluoresces yellow in the blue (or UV) light, the yellow and blue combine to form an apparent white. (there is no such thing as white light, of course). It's the same principle in LEDs and fluorescent lighting.
I'm actually hoping for a more orange light, I have Cree tri amber and tri red-orange coming in tomorrow. I'm hoping one of them is close to what I'm going for. If not I may try a custom amber/red or red-orange/blue so I can also get a good clash effect.