gem vs transparent gem

gem and transparent gem both are nouns.

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

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

gem: a crystalline rock that can be cut and polished for jewelry
transparent gem: a gemstone having the property of transmitting light without serious diffusion

Other hyponyms of gem include cabochon, opaque gem, semi-precious stone.

gem (noun)	transparent gem (noun)
a precious or semiprecious stone incorporated into a piece of jewelry	a gemstone having the property of transmitting light without serious diffusion
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