Prior to appraisal, each Stone of Barenziah is labeled as an "Unusual Gem". Once the first stone is found, there will be a miscellaneous objective that activates and indicates that the next step is appraisal. The city of Riften has two people capable of handling this task: Maul, an associate of Maven Black-Briar, and Vex, a member of the Thieves Guild.
After the appraisal, it is learned that a total of twenty-four Stones of Barenziah exist, which activates the quest No Stone Unturned. The stones are quest items of 0.5 weight and worth 200 gold, and they cannot be removed from the inventory until the entire set is obtained. Many of these stones can be found while completing small jobs for Vex and Delvin of the Thieves Guild. [Source: wikia]
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