Star spinel is a rare variety of spinel that exhibits asterism, a phenomenon where a star-shaped light effect appears on the surface of the gemstone. This occurs due to the presence of aligned needle-like inclusions within the stone that reflect light in a symmetrical pattern. Typically, the star effect is visible under direct light, and the most common star spinel has a four-rayed star, although six-rayed stars are also possible. The value of a star spinel can be quite high, especially for stones that display a clear, well-centered star against a richly colored background.
