gradate
    v 1: arrange according to grades; "These lines are gradated"
    2: pass imperceptibly from one degree, shade, or tone into
       another; "The paint on these walls gradates but you don't see
       it"

Gradate \Gra"date\, v. t. [See Grade.]
   1. To grade or arrange (parts in a whole, colors in painting,
      etc.), so that they shall harmonize.
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   2. (Chem.) To bring to a certain strength or grade of
      concentration; as, to gradate a saline solution.
      [1913 Webster]