neutral vs pearl grey

neutral is a noun but pearl grey is not a noun.

Word	Noun	Adjective	Verb	Adverb
neutral	Yes	Yes	No	No
pearl grey	No	Yes	No	No

neutral (noun)	pearl grey (noun)
one who does not side with any party in a war or dispute

neutral (adjective)	pearl grey (adjective)
having no hue	of a grey with a pearly tinge
possessing no distinctive quality or characteristics
lacking distinguishing quality or characteristics
not supporting or favoring either side in a war, dispute, or contest
having no personal preference
having no net electric charge
having only a limited ability to react chemically; chemically inactive