'lousy with diamonds'
This is a kind of slang, often associated with a style of writing from the 1930s-1950s involving private detectives.
Instead of saying, the woman was attractive, the author might write:
"She had more curves than the Monte Carlo Grand Prix, and twice as dangerous."
'lousy with rocks' is not an idiom, or usual expression, but a writer playing with words to create an image, and atmosphere.
'lousy' means full of fleas, and 'rocks' is slang for gems, particularly diamonds. So, she had as many diamond rings as a dog has fleas.
Instead of writing, "She had many diamond rings on her fingers", he is more likely to write: "Her fingers were lousy with rocks - as much ice on her hands as the iceberg that passed for this dame's two-timing heart."
ice : another informal word for 'diamonds'
rock : informal for precious gem, especially a diamond
so you could use either of them without any adjective - but in everyday conversation?!.