The process in which a relatively unspecialized cell acquires the specialized features of an iridophore. Iridophores are pigment cells derived from the neural crest. They contain guanidine or other purine crystals deposited in stacks called reflecting platets or iridisomes. This gives them a silver, gold, or iridescent appearance. [ http://www.ncbi.nlm.nih.gov/pubmed/11858836 GOC:mh GOC:jid ]