The Silver Amulet Box is the ninth treasure that can be found in Uncharted 2: Among Thieves.
The Silver Amulet Box is found in Chapter 2 - Breaking and Entering. When you enter the court where Harry tells you to go left, just follow the left path like he said. Leading you to a roof-like structure you can jump over to, the next step is to drop down onto the guard below. After that, you can see there's a rectangular flower box, along the rightmost wall. If you keep an eye on it for a few moments, you will see a glimmer of a treasure. Simply walk up to the side of the flower box and claim your prize before running back to visit with Harry in front of the next door.