The Collaborative International Dictionary of English v.0.48:

Opalize \O"pal*ize\, v. t. [imp. & p. p. Opalized; p. pr. &
   vb. n. Opalizing.] [Cf. F. opaliser.]
   To convert into opal, or a substance like opal. --Lyell.
   [1913 Webster]