Discolored nails on one paw?

A friend's kitten has discolored toenails on one paw only. They look reddish and/or blackish, and also seem a bit brittle and rough (though I'm not 100 percent sure on the latter two). The nails on all his other paws are clear and healthy.

Do any of you have experience with this? What do you think it might be? I'll ask the vet, but I'm curious.

He's a spotted cat and has different colored paw pads all over. Might it be just a case of genetic pigmentation?

Are the toe pads on those claws darker coloured as well? It's most likely just a pigment thing, but I don't know for sure if cats can have that the way dogs can...

Sometimes cats with more then one color (like torties) may have different colored nails. If the paw pads are multi-color I would think that's the case with the nails. But if the nail is brittle and not normal like the other nails (other then the color difference) you might want to have a vet take a look next time he goes to there

Some of the pads on that paw are black, and others are white... but all the nails are discolored, I think. I'll check, though. I didn't know that torties could have different-colored nails. This is actually my first experience with a cat with multicolored pads.

Is this a new thing, or have they always been that way? My boyfriend's black cat has dark-colored nails. My mom's cat is a tortie, and she has one dark-colored nail and the rest are normal. It makes it a little bit harder to trim her nails because I can't see the quick, but otherwise she's fine.

It is likely to be pigmentation I would have thought. Does the kitten go outside? I ask because cats that are hit by cars dig their claws into the road as an instinctive reflex action and this can cause bleeding inside the nail, or torn off nails with bleeding from the nails.

I had an interesting experience at the vet the other day - she had a quick look at Radar's nails and questioned us as to whether he could have got into the road, obviously thinking that his claws looked odd - the idea of him living indoors and having his nails trimmed short is not that common in this part of England!

Two of Sadie's claws are black, but her vet confirms it's not a problem at all.

I couldn't say whether they've always been that color -- the kitten is fairly new, and no one had noticed the nails before.

I looked at them a second time and they weren't as dark as I thought. It does seem like it might be blood in the nail. The kitten doesn't go outside, but he plays like a maniac and is really rough, bouncing off of walls, hanging off of things by his claws, rappelling and falling off of stuff. I suspect that's what's behind it.