crystal clear vs perspicuous

crystal clear and perspicuous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
crystal clear	No	Yes	No	No
perspicuous	No	Yes	No	No

As adjectives, crystal clear and perspicuous are synonyms defined as:

crystal clear and perspicuous: (of language) transparently clear; easily understandable

Other synonyms of crystal clear include limpid, lucid, luculent, pellucid.

crystal clear (adjective)	perspicuous (adjective)
(of language) transparently clear; easily understandable	(of language) transparently clear; easily understandable
transmitting light; able to be seen through with clarity