diadem vs taj

diadem

noun
  • A crown. 

  • Regal power; sovereignty; empire—considered as symbolized by the crown. 

  • An ornamental headband worn as a badge of royalty. 

  • An arch rising from the rim of a crown (rarely also of a coronet), and uniting with others over its centre. 

verb
  • To adorn with a diadem; to crown. 

taj

noun
  • A crown worn by Indian princes as a sign of high rank. 

  • A tall brimless hat, usually conical or curved on top, worn in Muslim countries as a sign of distinction and prestige. 

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