First of all, you cannot get Zuz'sare's Charm before bringing her the Vorator Eggs. And once you got it, you can neither sell it nor throw it away (because it is a quest item). So whatever you think you sold, it wasn't the Charm. Maybe you confuse it with another kind of scroll with the same or a similar icon.
There is only one way you might have missed the Charm: If your inventory was full at the time you handed in the Vorator Eggs, the Charm is dropped to the ground and you get a warning message. If you ignore the warning and leave the Charm, it will be lost forever once the area resets, rendering the quest impossible to complete.
So do you remember any such warning? If not, it's likely that you received the Charm and maybe put it into the Bag of Holding or one of your chests. Have a look there (it displays as a plain sheet of parchment).
And just to be sure you are in the correct stage of the quest: What does your journal currently say?