stipple vs variegate

stipple

verb
  • To use small dots to give the appearance of shading to. 

noun
  • The use of small dots that give the appearance of shading; the dots thus used. 

variegate

verb
  • To change the appearance of something, especially by covering with patches or streaks of different colour. 

  • To add variety to something. 

  • To dapple. 

adj
  • variegated 

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