cobalt vs navy blue

cobalt

noun

  • Cobalt blue. 

  • A chemical element (symbol Co) with an atomic number of 27: a hard, lustrous, silver-gray metal. 

navy blue

noun

  • A dark blue color. 

adj

  • Having a navy blue color. 

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