I suspect that <a href="/wiki/Oneiric_Pearl" title="Oneiric Pearl">Oneiric Pearls</a> in inventory count for 100 favor each, as I have 1125 for 10 pearls and a <a href="/wiki/Barnacled_Headpiece" title="Barnacled Headpiece">Barnacled Headpiece</a>, and 375 for 3 pearls and a <a href="/wiki/Grasping_Coral" title="Grasping Coral">Grasping Coral</a>

Edit: nvm, it must be due to having items from previous years in inventory (turns out it was <a href="/wiki/Skull_in_Coral" title="Skull in Coral">Skull in Corals</a>)