"Harry’s cloak is perfect," Hermione pressed on, "It belonged to his father, he probably had it while he was at Hogwarts. How many invisibility cloaks do you know that survive long enough to get passed down between generations? Surely Harry’s father used it a lot while he was a student, and God knows Harry used it all the time when he was here. Something that got  so  much use, and it never shows any sign of wear, the invisibility spell never loses its effect. Don’t you think that’s suspicious, at the very least?" 