navy blue vs blueness

navy blue and blueness both are nouns.

Word	Noun	Adjective	Verb	Adverb
navy blue	Yes	No	No	No
blueness	Yes	No	No	No

As nouns, blueness is a hypernym of navy blue; that is, blueness is a word with a broader meaning than navy blue:

navy blue: a dark shade of blue
blueness: blue color or pigment; resembling the color of the clear sky in the daytime

Other hypernyms of navy blue include blue.

navy blue (noun)	blueness (noun)
a dark shade of blue	blue color or pigment; resembling the color of the clear sky in the daytime