Vex reveals that the Crown of Barenziah is actually a paragon for the Thieves Guild. Recovering the crown restores the paragon to its full status. The fully restored Crown of Barenziah then sits on the mannequin bust in The Ragged Flagon - Cistern.
- It is impossible to equip the crown. When on its bust, the Crown only offers an "Activate" option.
- The crown has 25 gems, even though you collect 24, since one never departed from it.