richens

/R IH1 K AH0 N Z/
verb
  1. 1

    To make or render rich or richer.

  2. 2

    To become rich or richer; become superior in quality, condition or effectiveness.

  3. 3

    (of a colour) To gain richness; become heightened or intensified in brilliancy.

Source: https://en.wiktionary.org/wiki/richen, https://en.wiktionary.org/wiki/richens