Instructions
Talk to Robeira located in El Nath. Accept the "Evidence of The Seal" quest.
Use the dimensional portal in El Nath located in Shammos's solitary room. Enter the Ice Ravine entrance. Slash monsters with your weapon and keep going through the ravine until you reach the end of the cave where Rex is.
Slash Rex with your weapon until he is defeated. Use the mouse button to click on his body and a box will show up with the earrings. Click on the earrings to loot them.