The Collaborative International Dictionary of English v.0.48:

Iridize \Ir"i*dize\, v. t. [imp. & p. p. Iridized; p. pr. &
   vb. n. Iridizing.]
   [1913 Webster]
   1. To point or tip with iridium, as a gold pen.
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   2. To make iridescent; as, to iridize glass.
      [1913 Webster]