unfading vs amaranthine

unfading and amaranthine both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unfading	No	Yes	No	No
amaranthine	No	Yes	No	No

As adjectives, unfading and amaranthine are synonyms defined as:

unfading (adjective)	amaranthine (adjective)
of an imaginary flower that never fades	of or related to the amaranth plant
	of an imaginary flower that never fades