blue angel vs lapis lazuli

blue angel

noun
  • A blue flame produced by lighting one's flatus. 

  • A mollusc of genus Glaucus. 

lapis lazuli

noun
  • A deep, bright blue, like that of the stone. 

  • A deep-blue stone, used in making jewelry, and traditionally used to make the pigment ultramarine. 

adj
  • Of a deep, bright blue, like that of the stone. 

How often have the words blue angel and lapis lazuli occurred in a corpus of books? (source: Google Ngram Viewer )