"the cold crystalline water of melted snow"
"crystal clear skies"
"could see the sand on the bottom of the limpid pool"
"lucid air"
"a pellucid brook"
"transparent crystal"

"writes in a limpid style"
"lucid directions"
"a luculent oration"
"pellucid prose"
"a crystal clear explanation"
"a perspicuous argument"