Single Sight

In each grid, place 5 gems in empty squares. Every single square in which there is only one (horizontal, vertical, or diagonal) direction in which gems can be seen from that square contain an eye.

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
The solutions are here.