Amulet of Stone Protection

This amulet is made of a stone disc about an inch and a half diameter by a quarter inch thick and a strong silvery metal chain. The disc is carved with what looks like a humanoid in a Vetruvian Man pose, but the proportions are off. The torso is much larger and the limbs shorter. The various body segments look more like arranged stone boulders than flesh. Tiny runes are carved on the outside of the disc where the ridges on a Quarter would be.