if i recall my art class correct, the only reason you can see color on ant object is because the object absorbs certain light and reflects others.

black is only black because it absorbs all light and reflects none.
black is not actually a colour, its a shade.

same with white, its not a colour either, its what you see when all light is reflected.

using colured reflectors would be absorbing part of the spectrum, the only reason anyones eyes see colour,is because the object they are looking at is absorbing parts of the light souce thats hitting the object, and whats reflected is only part of the spectrum of light thats hitting it. and whats lrft is bouncing off...hence you seeing a colour rather than white.

in short terms...your reflector should be passive ie: metalic silver or white.