Hiding Horcruxes In Plain Site

There is no denying J.K. Rowling is a GENIUS. I love her so much and I think it has a lot to do with this hidden throw away lines she puts in her books, similar to Moffat's throw away lines in Doctor Who. Having seen majority of the movies before reading all the books, I had a unique perspective on things and was able to notice details others might have over looked (what can I say just call me Hermione Granger). I am sure I am not the first to notice this, though I have mentioned it to a few friends who were shocked by what I am about to tell you. We all know J.K Rowling likes to bring back insignificant things from early books and make then SUPER important, take Grindewald (mentioned in the first book on the back of Dumbledore's Chocolate Frog Card) or the Vanishing cabinet Harry hid in the second book which becomes the Death Eaters way into Hogwarts in the sixth book. I know in an interview J.K. Rowling mentioned how she thought it was funny no one noticed that the snake from the first book is actually Nagini, which isn't that funny cause its not super obvious. However these two hidden Horcuxes are! The first one is in the 5th book when everyone is helping to clean up Grimmauld Place. They are all cleaning out an old cabinet and there are a list of random things they find inside. Nothing to striking right. Except the fact that they find a gold locket that no one seems to be able to open. I feel on further inspection this one is a bit more obvious considering we later learn Mundungus went back and stole it from Grimmauld Place, among other things, but still pretty sneaky. This next one is actually my favorite and the one I think most people do not get. In the Half Blood Prince, Harry goes into the room of Requirement to hide the Prince's copy of Advance Potion Making. In order to remember where he left it, he uses an old Tiara to mark the spot. Thats right a Tiara also known as a diadem which turns out to have belonged to Rowena Ravenclaw. I am shocked more people did not notice this considering the Tiara was even mentioned in this book. Anyways perhaps I am underestimating people and its just my friends who are missing these details but I still thought it was pretty damn cool!!!