cobalt blue vs peacock blue

cobalt blue and peacock blue both are nouns.

Word	Noun	Adjective	Verb	Adverb
cobalt blue	Yes	No	No	No
peacock blue	Yes	No	No	No

As nouns, cobalt blue and peacock blue are synonyms defined as:

Other synonyms of cobalt blue include aqua, aquamarine, greenish blue, turquoise.

cobalt blue (noun)	peacock blue (noun)
a shade of blue tinged with green	a shade of blue tinged with green
greenish-blue pigment consisting essentially of cobalt oxide and alumina