jewel vs watch glass

jewel

noun
  • A bearing for a pivot in a watch, formed of a crystal or precious stone. 

  • A precious or semi-precious stone; gem, gemstone. 

  • A valuable object used for personal ornamentation, especially one made of precious metals and stones; a piece of jewellery. 

  • Any of various lycaenid butterflies of the genus Hypochrysops. 

  • The clitoris. 

  • Anything precious or valuable. 

verb
  • To bejewel; to decorate or bedeck with jewels or gems. 

watch glass

noun
  • The glass covering of the face of a watch. 

  • A sandglass. 

  • An item of glass laboratory equipment consisting of a simple, slightly concave circle of glass. It is a general utility item, used to hold small samples, to evaporate liquids, to cover a beaker, and so on. 

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