|“||You're not gonna believe this. It's called the Baozhu. It's one of eight ancient Chinese treasures. I-It's a pearl that grants wishes. Sort of. (...) Well, technically its supposed to give you "what your heart desires."||”|
The Baozhu was a pearl and one of eight ancient Chinese treasures that could grant the heart's desire of the user.
At an unknown point, Terry was able to find the Baozhu and add it to his extensive collection of occult objects. After Terry's death, the collection, including the Baozhu, fell into the hands of Sam and Dean Winchester whose interest was drawn by the pearl as they saw it as a way to get rid of Michael. However, their plans were temporarily foiled when Max stole the Impala and the collection.
After recovering the car and collection, the Winchesters took it to the Men of Letters bunker where Dean attempted to use the Baozhu to get rid of Michael. Instead, the Baozhu brought John Winchester forward in time from 2003 due to Dean's long held desire to have his family back together. As a side effect of John's disappearance in the past, an alternate timeline was created where Sam and Dean never started hunting together, drastically altering the past.
After a fight with the alternate timeline Zachariah and Castiel, the Winchesters decided to return John to 2003 to put history back on track. After an emotional goodbye, Sam smashed the Baozhu to dust with a small bowl and John almost instantly faded away. John was returned to 2003, restoring history to normal. John woke up in the front seat of the Impala and believed the entire experience was a great dream despite predictions that he would remember nothing once the Baozhu's destruction unwound the timeline.
The Baozhu appeared like a white pearl, however, it shape was not as smooth like usual pearl and a bit rough.
The Baozhu could grant the deepest desire of the user. All the user had to do was to hold the pearl and concentrate for the Baozhu to grant their wish. While the user might believe that their deepest desire they were using the Baozhu to bring to life was one thing, they could potentially be wrong. The Baozhu worked off of the user's subconscious deepest desire, not what the person may consciously want.
The Baozhu's power to grant wishes was incredible, but it had its limits. When Dean Winchester's deepest desire was to have his family back together, the Baozhu could not resurrect John Winchester. However, it had the power to pull him from the year 2003 and bring John to 2019 to fulfill Dean's wish.
To reverse the Baozhu's wish granting, the pearl simply had to be destroyed. The destruction of the Baozhu would unwind the wish like it had never happened, though those directly affected would remember the events. When John Winchester was returned to 2003, he was left thinking that his time trip was simply a dream while the alternate timeline created by his disappearance was erased from existence.