Cats eyes - color change

Question
We took in a stray cat about a month ago.  We took her to the vet and were happy to learn she is in good health and about six months of age.  We've had her about two weeks.  She is all black.  Her eyes have been so black, it was difficult to tell if they are open or closed.  Why would her eyes suddenly, overnight, turn amber with the pupil being black, of course?  Here eyes seem to be healthy, and she is her usual active self.  

Answer
I can't say I've ever seen a cat with black eyes.  Amber is usually a normal, healthy color for a cat's eyes.  But I must say that any sudden change in eye color should be cause for concern.  

When a cat's irises begin turning from their normal color to a yellow, green or rust color, this can indicate a condition called uveitis.  It's an inflammation of the globe of the eye.  While many cases of this have no known cause, it is a serious symptom that often stems from serious illnesses.  When the eye starts turning a deep golden to brown color, this can indicate that red blood cells are being deposited in the eye, which is abnormal.  It can be caused by anything from an eye injury to terminal illnesses like feline leukemia.

I would say to call the vet and ask if you should be concerned.  If she was not tested for feline leukemia and feline AIDS, I would definitely recommend bringing her back to the vet to have that done.  These diseases are contagious (leukemia much moreso than AIDS), incurable, and cats who have them will need special care.