Awareness (Rare). You can’t be surprised while this dark blue rhomboid orbits your head.

The stone can't be this type; the man was very much surprised.

So it must be one of these:

Strength (Very Rare). Your Strength score increases by 2, to a maximum of 20, while this pale blue rhomboid orbits your head.

+20 to Dangerous

Insight (Very Rare). Your Wisdom score increases by 2, to a maximum of 20, while this incandescent blue sphere orbits your head.

+20 to Watchful