x1's eye(s)/iris(es) is/are hazel as perceived by x2 under conditions x3
Hazel in this context is a brown and/or gold color that is mixed with or has a tint of green (or vice-versa). Really, only objects that have qualities similar to eye irises can be hazel; other combinations of brown and green do not necessarily constitute hazel (rather, they are often a muddy green or a mossy brown), but if the object has these qualities sufficiently, it may qualify. The point is that not all brown-greens are hazel. This color is distinct from amber.