From anterior (front) to posterior (back), the layers of the iris are: The stroma and the anterior border layer of the iris are derived from the neural crest, and behind the stroma of the iris, the sphincter pupillae and dilator pupillae muscles as well as the iris epithelium develop from optic cup neuroectoderm.
Iris Ceramica in the new Milan Iris Ceramica Group flagship store. Even though the ancestors of the Irish Celts were scorching brunettes, they loved to paint hair in red color.

National Eye Institute. Interference effects can occur at both molecular and light microscopic scales, and are often associated (in melanin-bearing cells) with quasi-crystalline formations which enhance the optical effects.