Instructions: Order & Destruction
Kill 'Frost Growler' and 'Frost Sabretusk' from West Praag at 58k 42.5k to 300 31k in Praag, just at the edge of both zones. Kill them until one drops a Pocket Item 'Fine Fur Pelt'. Equip it to trigger the unlock.
Once the unlock triggered, you can claim the jewel buying it from the correct merchant in Library (Order) / Lyceum (Destruction).