the Phantomhive ring - When Lizzy threw it and it shattered into pieces, how exactly did Ciel get it back in one piece? Did Sebastian collect all the pieces and glue-fix it back together again(with demon magic/power?), or did Sebs just give a well-made copy of it to Ciel? Does our Ciel still have the ring, or does real Ciel now have it?
Our earl already has the repaired ring by the end of ch2, and Sebastian must have used his powers to fix it so quickly and so perfectly. Sebastian might have difficulty with fabrics(?), but metals are something demons are often said to manipulate easily. If the stone actually broke, Sebastian might have been able to repair that magically, too.
And he still has it, since he wears it (almost) everywhere he goes. Rare exceptions to this would be hanging out in the alley to catch Jack the Ripper, spending time with the circus troupe, and going to Sphere Music Hall as a working-class boy. He might have even worn it to Druitt’s party; I don’t recall.
I expect real Ciel will tell our earl that he can return the ring to “its rightful owner” now. Sadly, our earl might not have much of a choice.