pearl necklace vs rivière

pearl necklace

noun
  • Used other than figuratively or idiomatically: see pearl, necklace. 

  • A sexual act whereby semen is ejaculated onto a partner's upper chest, breasts and/or throat. 

rivière

noun
  • A necklace of diamonds or other precious stones, especially one of several strings. 

How often have the words pearl necklace and rivière occurred in a corpus of books? (source: Google Ngram Viewer )