SHINY
Shiny black
Generally, dull black
Yes, shiny black absorbs less sunlight than dull black. Shiny surfaces reflect more light, so less heat is absorbed compared to dull surfaces which absorb more light and heat.
It is in fact the best radiator. Dull black is the best absorber and emitter. Then shiny black, followed by white, then silver. While the best reflector goes the other way around (silver's the best, then white, followed by shiny black, then dull black)
Coal is generally dull in appearance, with a matte or non-reflective surface. It typically has a dark, black color and doesn't have a shiny or metallic lustre.
Sodium is shiny, but it reacts very quickly with oxygen in the air to form lithium oxide, which is a dull black color.
dull
Naturally occurring boron is dull, but it can be polished.
dull
shiny
Shiny
It is shiny.