Gray stone

A gray stone is one of a flint stone, loadstone, touchstone, or luckstone. Distinguishing these is fairly easy, as follows.

The loadstone can be distinguished by attempting to kick it when it is on the ground; unless your character is very strong the loadstone will not move and produce a "Thump!" instead. Rubbing an item on the touchstone will produce its signature "scritch, scritch" and can be identified through this.

A somewhat dubious way of distinguishing flint stones from luckstones is attempting to name them "The Heart of Ahriman"; if the stone is a luckstone your hand will slip as it is not possible to name the base item of an artifact after its artifact. This behaviour is sometimes viewed as unintentional and can be frowned upon in some circles.