blackness vs sable

blackness and sable both are nouns.

Word	Noun	Adjective	Verb	Adverb
blackness	Yes	No	No	No
sable	Yes	Yes	No	No

As nouns, sable is a hyponym of blackness; that is, sable is a word with a more specific, narrower meaning than blackness:

blackness: the quality or state of the achromatic color of least lightness (bearing the least resemblance to white)
sable: a very dark black

Other hyponyms of blackness include coal black, ebony, jet black, pitch black, soot black.

blackness (noun)	sable (noun)
the quality or state of the achromatic color of least lightness (bearing the least resemblance to white)	marten of northern Asian forests having luxuriant dark brown fur
total absence of light	a scarf (or trimming) made of sable
	an artist's brush made of sable hairs
	a very dark black
	the expensive dark brown fur of the marten

blackness (adjective)	sable (adjective)
	of a dark somewhat brownish black