The Moving Star on the Gem's Surface Star sapphire is a sapphire variety of corundum that displays the optical phenomenon known as asterism. When illuminated by a single point light source, light rays appear to float above the gem's curved surface and shift position as the stone or the light angle moves.
Beauty Born from Internal Needles Asterism is created by light reflecting off microscopic mineral needles arranged in multiple orderly directions within the corundum crystal matrix. Most star sapphires exhibit a six-rayed star, though four-rayed stars occasionally occur, while twelve-rayed stars are exceptionally rare.
Color Variety and Quality Evaluation Star sapphires are found in a wide range of body colors, including light blue, deep blue, gray, violet, pink, yellow, green, brown, and deep near-black tones. Red corundum is classified as ruby, and when displaying a star, it is termed star ruby. Evaluating a star sapphire requires considering body color, star sharpness and completeness, transparency, cabochon shape and dome height, and overall clarity. A top-quality star features straight, sharp, continuous rays that intersect near the dome center and glide fluidly under light.
The moving star that glides across the dome of a star sapphire originates from neatly oriented microscopic inclusions and relies on precise cutting alignment.
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