cyelon sapphires

Asterism

In gems, an asterism is a star-shaped reflection of light. To appreciate the uniqueness of this stone, it is necessary to understand the rarity and complexity of the star’s creation.

Sub-microscopic crystals of a mineral called rutile cause fine needle-like inclusions within the sapphire. These form a six-sided star shape in a truly miraculous way.

The asterism, or star-effect, is caused by the difference in refractive index between the sapphire and that of the dense fibers of rutile. The refractive index of sapphire is usually between 1.760 and 1.778, which is much lower than that of rutile. Light reflects from the fine inclusions of rutile aligned perpendicularly to the rays of the star. With such precision found only in nature, star sapphires are a marvel to behold.