I got 2 guinea pig about a week a go and I notice today that on of the eyes of one of them it s blue and it was never like that is she sick?

Is it acting different? Lethargic? Tired? Runny nose? My cats eyes change color a lot but I'm unsure what that means with Guinea pigs. I'd watch it. If it acts differently I'd call a vet and ask them.

Try taking her to the vet, I hope she gets better!

Some animals just do have different coloured eyes - like some collie dogs.
If there is no other sign of trouble - be happy - you have one very good looking wee piggie - bit like David Bowie!!

Would you have a photo?

yeah it might be. Call a animal doctor