Amber eyes are of a solid color and have a strong yellowish/golden and russet/coppery tint. This might be due to the deposition of the yellow pigment called lipochrome in the iris (which is also found in green eyes).[21][22] Amber eyes should not be confused with hazel eyes; although hazel eyes may contain specks of amber or gold, they usually tend to comprise many other colors, including green, brown and orange. Also, hazel eyes may appear to shift in color and consist of flecks and ripples, while amber eyes are of a solid gold hue.
The eyes of some pigeons contain yellow fluorescing pigments known as pteridines.[23] The bright yellow eyes of the Great Horned Owl are thought to be due to the presence of the pteridine pigment xanthopterin within certain chromatophores (called xanthophores) located in the iris stroma.[24] In humans, yellowish specks or patches are thought to be due to the pigment lipofuscin, also known as lipochrome. - http://en.wikipedia.org/wiki/Eye_color#Amber