Thin film interference (a primary factor in iridescence) is a naturally occurring phenomenon in which two out of phase rays of light interfere creating an interesting interference pattern.
I've been experimenting with this phenomenon and am currently recreating a physically accurate model of this using Cycles shaders.
Examples:
Oil on water
Heat treated metals
Bubbles
Read more on thin film interference: https://en.wikipedia.org/wiki/Thin-film_interference
@jlampel It does increase render time and the required samples quite significantly, and it's nearly impossible to apply it to a non-planar model. But still, it's a step in the right direction.
That's awesome, does the effect increase render time a bit or is it fairly quick?