unappreciated vs unvalued

unappreciated

adj
  • Not deemed to have any value, valueless, worthless, not appreciated. 

  • Not having risen in value 

unvalued

adj
  • Not considered to be of worth; deemed valueless. 

  • Not having been valued or appraised. 

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