Oxford blue vs turquoise

Oxford blue

adj

  • Of an Oxford blue colour. 

noun

  • A dark blue colour. 

turquoise

adj

  • Having a pale greenish-blue colour. 

  • Made of turquoise (the gemstone). 

noun

  • A sky-blue, greenish-blue, or greenish-gray semi-precious gemstone. 

  • A pale greenish-blue colour, like that of the gemstone. 

  • turquoise 

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