emerald green vs virescent

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. 

virescent

adj

  • Green-like, greenish. 

  • Becoming green. 

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