cabochon vs gem

cabochon and gem both are nouns.

Word	Noun	Adjective	Verb	Adverb
cabochon	Yes	No	No	No
gem	Yes	No	No	No

As nouns, gem is a hypernym of cabochon; that is, gem is a word with a broader meaning than cabochon:

Other hypernyms of cabochon include gemstone, stone.

cabochon (noun)	gem (noun)
a highly polished gem that is cut convexly but without facets	a precious or semiprecious stone incorporated into a piece of jewelry
	art highly prized for its beauty or perfection
	a sweet quick bread baked in a cup-shaped pan
	a person who is as brilliant and precious as a piece of jewelry
	a crystalline rock that can be cut and polished for jewelry