Star sapphire is rare variety of sapphire that exhibits a rare asterism under specific lighting. When viewing star sapphire, a six-rayed star will appear to float across the surface of the stone. The effect is best viewed under a direct light source and while tilting and rotating the stone from different angles. Star sapphires contain unusual tiny needle-like inclusions of rutile. Aligned needles that intersect each other at varying angles produce the rare phenomenon known as asterism. Star sapphires can range in color from blue in various tones to pink, orange, yellow, green, lavender, gray or black. The most desirable color is a vivid, intense blue. Most star sapphire exhibits a white star, but star sapphire from Thailand is famed for its gold colored asterism.