of the highest quality vs sterling

of the highest quality

sterling

noun
  • The currency of the United Kingdom; especially the pound. 

  • A structure of pilings that protects the piers of a bridge; a starling. 

  • Sterling silver, or articles made from this material. 

  • Former British gold or silver coinage of a standard fineness: for gold 0.91666 and for silver 0.925. 

adj
  • Of, or relating to British currency, or the former British coinage. 

  • Of, relating to, or made from sterling silver. 

  • Of acknowledged worth or influence; high quality; authoritative. 

  • Genuine; true; pure; of great value or excellence. 

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