Due to the crystal growth characteristics of garnet, there are sometimes three groups of "rutile fibrous inclusions" arranged in parallel with an included angle of 120 degrees, and the growth direction of these three groups of inclusions is perpendicular to the crystal axis. When it is cut and ground into an arc-shaped gem along the crystal axis, it will present six starlight on the arc surface.

Hexagonal starlight is formed by the intersection of six interlaced bands of light in the center of a gem.

Under the irradiation of parallel light, two or more intersecting bright lines appear on the surface of some cut and polished jewels and jade, which is called starlight effect.