The Tibetan Coral Earring is the eighty-sixth treasure that can be found in Uncharted 2: Among Thieves.
The Tibetan Coral Earring is found in Chapter 23 - Reunion. Once you've shimmied right until you can't anymore, you'll be able to pull yourself up onto a broken stone pathway. The way forward is directly ahead of you, as you'll have to use the wooden beams sticking out of the side of the building to swing forward.
But before doing that, drop down to the half-destroyed rooftop directly below you, to the right. Once you've dropped down, look up and to the left. Hanging underneath the stone pathway you were just traversing is the treasure. Simply shoot it down and walk up to it to grab it once it's fallen to the snowy ground.