Brytthel will suggest that you speak to the Glaufaye about protecting the Queen's jewel.
Leave the city for Thalumbra and speak to Elanluelle at -486.86,236.58,343.23 . She'll tell you to search Maldura's libraries for more information.
Return to the city and search the shelves in the Alcove of Reason for three references. Use the recipe "Research on Containing Magical Gemstones" to compile the notes. You'll need 1 thaumic incense for this combine.
Return the Brytthel to tell her what you've discovered for your reward.