Blue, brown, green and grey. Those are the eye colours we most commonly see. And I assume we are all humans. Oh and because of had so many comments on it; yes, hazel is also a common colour.
Different species have different eye colours I understand so like before, I'm applying this to human characters.
So unless a whole group of characters have unusual eye colours (e.g. Rose, Dave, Roxy and Dirk from homestuck) or your character has a problem with their eyes (e.g. Some sort of disease or had a past experience meaning they have different coloured eyes like David Bowie (R.I.P)), don't write that your character has unusual eyes.
I mean, beautiful and descriptive eyes are great. I love reading that. But natural red eyes in a human, not so much.
Of course, your character might be a mutant from X-men and they might have cat eyes or whatever. (I will be talking about powers later on).
Regardless of if your character is an X-man or has an eye disease thing, if you're writing them onto an everyday scenario (e.g. Common high school), you should make some of your other characters ask about it. Or at least point it out/acknowledge it in a curious way. This will make your character and those around them so much more realistic.
If I became friends with a girl who has different coloured eyes, I'd point it out even if it only was 'you have lovely eyes'.