The world I'm making isn't hard science fiction nor science fiction, really, but I'd like to be somewhat realistic in some aspects, like this one.
I'd like my humanoid fantasy/alien species to have teeth that aren't white or yellow-ish like those of most creatures on earth. The species are humanoid, omnivores, but have long and sharp incisors and canines. Their world is more or less earth-like though there are some minor differences (atmosphere density, pressure, gravity, etc.) which I don't think play much of a role here
I've looked at beaver teeth since those are orange/yellow and apparently that's due to the iron in the enamel. I'd rather not use orange teeth, though, and have gone down the research rabbit hole. Limpet-like teeth would be an option (giving blue-ish teeth, from google), but those are rated in tensile strength, which I don't think plays much of a role regarding teeth hardness? Could be wrong though. I thought about just taking a random organically occurring oxide (since beaver teeth contain iron oxide) and choosing one that's as high on the Moh scale of hardness as our teeth or higher, but that list is long and I'm not sure what would realistically make sense.
To summarise: What kind of material or chemical makeup could the teeth of a humanoid fantasy species have so that they aren't whitem except for iron (because I don't want them to have orange teeth)? Bonus points if that material somehow makes those teeth "stronger" which for teeth I assume would mean more durable and sharper. And dark tooth colours like black or dark blue would be the coolest