Iridescence
The word iridescence is derived in part from the Greek word ἶρις îris (gen. ἴριδος íridos), meaning rainbow, and is combined with the Latin suffix -escent, meaning "having a tendency toward".
Iris in turn derives from the goddess Iris of Greek mythology, the personification of the rainbow and acted as a messenger of the gods. Goniochromism is derived from the Greek words gonia, meaning "angle", and chroma, meaning "colour".
Iridescence is an optical phenomenon of surfaces in which hue changes with the angle of observation and the angle of illumination. It is often caused by multiple reflections from two or more semi-transparent surfaces in which phase shift and interference of the reflections modulate the incidental light, by amplifying or attenuating some frequencies more than others.
