In contrast solid metals are lustrous and do not absorb light.
Metals are the materials of choice for high reflectivity mirrors.
This effect is exploited in solar panel technology. Panels are covered first with a highly reflecting surface, and next with glass containing a suspension of metallic colloid - usually copper. Most of the sun's energy is strongly absorbed by the colloid, but that in the infra red region of the spectrum is lost. At infra red wavelengths solar panels behave like inside-out thermos flasks.