If you will all excuse me for a minute while I take this way to seriously: I compiled the quotes and pictures from the previous challenges into one place because I thought that it would be easier to find a pattern. I failed. I have found no definitive pattern. But I offer the compiled information to you all in the hopes that one of you is smarter than I am. Stay cunning brothers and sisters.
Some side notes about the formatting: the hyper links that were used are the original ones in the clues (I tried to keep the punctuation that was included as similar as I could but I may have made slight mistakes, and I apologize for that. The pictures have also been put back through imgur so the meta data may be different) The bold answer is the one that was correct for the round, we were not given the correct answer for number 2 so if anyone knows that one please let me know.
** The Diary was proof that he was the Heir of Slytherin. **
"The diary. My diary. Little Ginny's been writing in it for months and months, telling me all her pitiful worries and woes… So Ginny poured out her soul to me, and her soul happened to be exactly what I wanted
She opened the lid. Harry edged forward a little to get a better view and saw what looked like a small golden cup with two finely wrought handles.
Harry's wandlight passed over shields and goblin-made helmets set on shelves rising to the ceiling; higher and higher he raised the beam, until suddenly it found an object that made his heart skip and his hand tremble.
Then the second brother, who was an arrogant man, decided that he wanted to humiliate Death still further, and asked for the power to recall others from Death.
Harry saw that he was wearing Marvolo's gold-and-black ring; he had already killed his father.
The metal shell broke open... the black stone with is jagged crack running down the centre sat in the two halves of the Snitch. The Resurrection Stone had cracked down the vertical line representing the Elder Wand. The triangle and circle representing the Cloak and the stone were still discernible.
She slid back the fine filigree clasp and flipped open the box. There upon the smooth crimson velvet lay a heavy golden locket.
Dumbledore scooped the locket from the bottom of the stone basin and stowed it inside his robes.
To the Dark Lord I know I will be dead long before you read this but I want you to know that it was I who discovered your secret. I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when you meet your match you will be mortal once more.
He saw it out of the corner of his eye; panic made him turn and horror paralysed him as he saw the old body collapsing and the great snake pouring from the place where her neck had been.
"Dinner, Nagini, " said Voldemort softly, and the great snake swayed and slithered from his shoulders onto the polished wood.
Yeah, but the lost diadem is lost... that's sort of the point.
It's a kind of crown. Ravenclaw's was supposed to have magical properties, enhance the wisdom of the wearer.