Hmmm. Could the locket be back at 12 Grimmauld Place?
Not any more . Ch 6 in OOTP,remember when they were cleaning?
"Sirius sustained a bad bite from a silver snuff box; within seconds, his bitten hand had developed an unpleasant crusty covering like a tough brown Glove.
It's okay," he said, examining the hand with interest before tapping it lightly with his wand, and restoring the skin to normal. "must be Wartcap powder in there."
He threw the box aside into the sack they were depositing the debris from the cabinets; Harry saw George wrap his own hand carefully in a cloth moments later and sneak the box into his already doxy filled pocket."
Assuming Kreacher didn't hide it, or Mundungus Fletcher didn't fence it....