Then Harry took off his left shoe, and his left sock, and took off the toe-ring that was Hermione Granger, the Transfigured shape identical to the toe-ring that had been given Harry as an emergency portkey.
(Chapter 111)
“Dumbledore resumed his examination. Harry had to remove his left shoe, and take off the toe-ring that was his emergency portkey if someone kidnapped him and took him outside the wards of Hogwarts (and didn’t put up anti-Apparition, anti-portkey, anti-phoenix, and anti-time-looping wards, which Severus had warned Harry that any inner-circle Death Eater would certainly do). It was verified that the magic radiating from the toe-ring was indeed the magic of a portkey, and not the magic of a Transfiguration. The rest of Harry was deemed clear.”
The primary alternate hypothesis—that Hermione was transfigured to be his glasses—also requires there to be a transfigured object in his room that no one notices. It’s not a contradiction (since he would have the real ring and the Hermione ring, and wear the real one to visiting Dumbledore).
(Chapter 111)
(Chapter 94)
Before that meeting Harry fiddled briefly under his sheets. Maybe he took the Transfigured ring off and put the real one on at that time?
Alternatively, he might have used a different hiding-place for Hermione back then and only Transfigured her into the toe-ring later.
The primary alternate hypothesis—that Hermione was transfigured to be his glasses—also requires there to be a transfigured object in his room that no one notices. It’s not a contradiction (since he would have the real ring and the Hermione ring, and wear the real one to visiting Dumbledore).