Small Sapphire Quest/Spoiler

Requirements

 * Rope, or equivalent.

Method
Follow the path to Drefia (you will encounter Snakes, Scorpions, Nomads, Ghouls, and Tarnished Spirits) and you should appear here. The chest containing the reward is located here, and on your way there you should encounter Skeletons, Ghouls, Stalkers, and Demon Skeletons. The island itself contains two Pirate Skeletons and one Pirate Ghost. Contrary to how it may seem, you can simply walk over to the island and open the chest.