1) To cover with iridium 
to make iridescent
• (v. t.) To make iridescent; as, to iridize glass. • (v. t.) To point or tip with iridium, as a gold pen.
Ir'i·dize transitive verb [ imperfect & past participle Iridized ; present participle & verbal noun Iridizing .] 1. To point or tip with iridium, as a gold pen. 2. To make iridescent; as, to iridize glass. 
iridize, iridise (British); iridizing 1. To make iridescent; as, to iridize glass. 2. To point or tip with iridium; such as, a gold pen.
to cover with iridium.