lead crystal vs vitrics

lead crystal

noun
  • cut glass made of this material. 

  • glass that contains at least 24% lead oxide (PbO). 

vitrics

noun
  • The art or study of the manufacture and decoration of glassware. 

  • Articles of glassware collectively. 

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