Gem the cat is located in a cove near the water, south of the Cathedral, at 3pm. Gem asks you to find a man named Rubrio in Warrens to help brew a potion. Unfortunately, the Warrens are closed until midnight, so he will ask you to find two "Niblet Hairballs" for the potion. After getting the Starlet Spice, go to the Old Town Market to find Ronan's body (he's the boy in the green jacket). Upon completing this mission you will gain +80 HP, +12 Magic, 1600 Gil and the item "black cat ears"