A clue or two about a hue

Of this hue are certain starfish,

as well as the moor frog,

one in two million lobsters,

a fairly famous dog;

a lovely ringed octopus,

the hyacinth macaw,

the dragon-like ribbon eel

the polygamous peafowl;

the sky, when it is cloudless,

the Mediterranean Sea,

his eyes, full of starlight,

when they look at me;

my mood when I am lonely

when you are far away

when all is dark and dreary

each dawn, gloomy and gray.