i am not an expert here at all but my understanding is that there are some green iguanas that are born blue and turn color about a year or so to green. However there are also blue morphs that will keep their blue or turquoise color. these of course would be considered much rarer and i think it depends on where the originated from. I have some that are bright turquoise and have seen some even close to navy blue. no green at all and if they turn green it is under certain lamps.