chalcedony vs cornelian

chalcedony and cornelian both are nouns.

Word	Noun	Adjective	Verb	Adverb
chalcedony	Yes	No	No	No
cornelian	Yes	No	No	No

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

Other hyponyms of chalcedony include agate, bloodstone, heliotrope, carnelian, chrysoprase, onyx, plasma, sard, sardine, sardius.

chalcedony (noun)	cornelian (noun)
a milky or greyish translucent to transparent quartz	a translucent red or orange variety of chalcedony