The Fibula Thogchag is the ninety-seventh treasure that can be found in Uncharted 2: Among Thieves.
The Fibula Thogchag is found in Chapter 25 - Broken Paradise. As you push forward on the broken platforms overlooking the watery route below, you'll be able to grab another treasure. As you push forward, you'll see treasure's glimmer up above on the building to your left. All you have to do is spot the treasure and shoot it down. Then, simply walk to where it lands on one of the broken platforms, and claim it as your own.