Final answer:
The characteristic color of a reflection nebula is blue, due to the efficient scattering of blue wavelengths by small dust grains within the nebula.
Step-by-step explanation:
The characteristic color of a reflection nebula is blue. This phenomenon occurs because the dust grains within the nebula scatter light with blue wavelengths more efficiently than those with red wavelengths. As a result, a reflection nebula typically presents a bluish hue, as seen in the well-known Pleiades cluster. This scattering process is a consequence of the small size of the dust grains in the nebula. In the context of Astronomy, other effects like interstellar reddening can occur where dust grains also absorb some starlight.