The Intricate Gold Ring is the twelvth treasure that can be found in Uncharted: Drake's Fortune.
The Intricate Gold Ring is found in Chapter 4 - Plane-wrecked. After killing the numerous pirates in the large open area, climb up the pillars and follow the pillar to the end. Jump to the platform (there should be an exploding barrel here if you haven't shot it yet). The treasure is in the corner of this platform, near a small boulder.