Sunstones

Sunstone is the gem where the inclusions are the point. Tiny platelets of copper or hematite lie in parallel planes inside the crystal, and when light reaches them they flash together in a warm metallic spangle — aventurescence, the trade calls it. A cleaner sunstone is not a better one here; take the shimmer out and you have plain feldspar.

Tilt one under a single light rather than diffuse daylight, which is where the effect shows best. At Mohs 6 to 6.5 it suits earrings and pendants. Standard millimeter sizes, ready to set.