First try to work out whether there is any treasure in the chest in the middle.
The lights at the top-left and bottom-right both say '2'.
If the middle treasure chest was empty, that would mean there were two jewels in both the top-left and the botto-right, making a total of four.
In other words, the middle treasure chest can't be empty.
Continuing on from hint two...
There is a jewel in the treasure chest in the middle.
Now you need to look at the lights at the top-right and bottom-left to figure out which chests don't contain any jewels.
Continuing on from hint three...
The lights at the top-right and bottom-left both say '1'.
We know that there is a jewel in the middle treasure chest, so there can't be jewels in those chests.
This means that the jewels are hidden in chests that are not within range of those lights.
Answer for 'Treasure Hunt'
The answer is as follows.