coal-black vs jet-black

coal-black and jet-black both are adjectives.

Word	Noun	Adjective	Verb	Adverb
coal-black	No	Yes	No	No
jet-black	No	Yes	No	No

As adjectives, coal-black and jet-black are synonyms defined as:

coal-black and jet-black: of the blackest black; similar to the color of jet or coal

Other synonyms of coal-black include jet, pitchy, sooty.

coal-black (adjective)	jet-black (adjective)
of the blackest black; similar to the color of jet or coal	of the blackest black; similar to the color of jet or coal