eau de Nil vs emerald green

eau de Nil

emerald green

adj

  • Of a rich green colour, like that of an emerald. 

noun

  • A rich green colour, like that of an emerald. 

  • A durable vivid green pigment made from copper arsenate. 

How often have the words eau de Nil and emerald green occurred in a corpus of books? (source: Google Ngram Viewer )