stone-grey vs slate-grey

stone-grey and slate-grey both are adjectives.

Word	Noun	Adjective	Verb	Adverb
stone-grey	No	Yes	No	No
slate-grey	No	Yes	No	No

As adjectives, stone-grey and slate-grey are synonyms defined as:

Other synonyms of stone-grey include slate-gray, slatey, slaty-gray, slaty-grey, slaty, stone-gray.

stone-grey (adjective)	slate-grey (adjective)
of the color of slate or granite	of the color of slate or granite