emerald vs transparent gem

emerald and transparent gem both are nouns.

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

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

emerald: a green transparent form of beryl; highly valued as a gemstone
transparent gem: a gemstone having the property of transmitting light without serious diffusion

Other hypernyms of emerald include beryl.

emerald (noun)	transparent gem (noun)
the green color of an emerald	a gemstone having the property of transmitting light without serious diffusion
a transparent piece of emerald that has been cut and polished and is valued as a precious gem
a green transparent form of beryl; highly valued as a gemstone