cobalt blue vs olive green

cobalt blue

adj
  • Of the color of the pigment zaffre. 

noun
  • A deep blue pigment derived from cobalt; zaffre. 

olive green

adj
  • Having this hue. 

noun
  • A green-yellow hue that is brighter and greener than olive. 

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