The Mani Jewel Thogchag is the ninety-ninth treasure that can be found in Uncharted 2: Among Thieves.
The Mani Jewel Thogchag is found in Chapter 25 - Broken Paradise. Acquiring this treasure is easy, though you'll definitely want to wait until the fray in this large chamber has subsided before actually going after it. At the center of the chamber, there's a huge torch surrounded by statues and other ornate objects. If you take a look at all angles of the torch, you'll no doubt spot the treasure in question hanging off of the tip of one of the statues' fingers. Simply shoot it down to ground level and pick it up. You're only a couple of treasures away from having them all!