Star sapphire

A star sapphire is a remarkable variety of corundum that displays an optical phenomenon known as asterism, which manifests as a star-like pattern on the surface of the stone. This natural wonder makes star sapphires one of the most sought-after and unique gemstones in the world.

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Red corundum gemstones are classified as rubies, while other colors belong to the sapphire family. Star sapphires owe their stunning visual effect to intersecting needle-like inclusions, often composed of rutile. These inclusions align with the crystal’s internal structure, resulting in a mesmerizing six-rayed star pattern when viewed under a single overhead light source.

To best showcase the asterism, star sapphires are typically cut as cabochons with a high dome. Ideally, the star’s center aligns perfectly with the top of the dome, enhancing its visual appeal.

Twelve-Rayed Star Sapphire Stone

In rare cases, star sapphires may exhibit a twelve-rayed star. This phenomenon occurs when two sets of inclusions, such as fine rutile needles and small hematite platelets, intersect at different angles within the crystal. The first set of inclusions creates a whitish star, while the second adds a golden hue, resulting in a dual-layered, twelve-rayed star.

During crystallization, these inclusions become oriented in specific directions, forming two distinct six-rayed stars that overlap to create the twelve-rayed effect. Imperfect or asymmetrical stars can also result from crystal twinning. Additionally, some star sapphires may display a cat’s eye effect instead of a star, depending on the orientation of the cabochon’s dome relative to the crystal’s c-axis.

If the dome is oriented slightly off-center, the star may appear displaced from the high point of the cabochon, affecting the stone’s symmetry but not its unique charm.

World Records

The **Star of Adam**, weighing an astounding 1,404.49 carats, holds the title of the largest star sapphire ever discovered. This exceptional gem was unearthed in the city of Ratnapura, known as the “City of Gems” in southern Sri Lanka.

The **Black Star of Queensland**, the second-largest gem-quality star sapphire, weighs 733 carats and is another marvel of nature.

Star of India Sapphire Gem

The **Star of India**, a magnificent star sapphire originating from Sri Lanka, weighs 563.4 carats and ranks as the third-largest known specimen. It is currently displayed at the American Museum of Natural History in New York City, captivating visitors from around the world.

Another notable example is the **Star of Bombay**, a 182-carat blue star sapphire also mined in Sri Lanka. This gemstone is housed at the National Museum of Natural History in Washington, D.C. Both stones exemplify the incredible allure and rarity of star sapphires.

The value of a star sapphire is determined by multiple factors, including its weight, body color, transparency, and the visibility and sharpness of its asterism. Stones with vivid body colors and well-defined stars command the highest prices.

Star sapphires untreated from Myanmar (Burma)

FAQ About Star Sapphires

What causes the star effect in a star sapphire?

The star effect, or asterism, is caused by needle-like inclusions, often composed of rutile, that align with the crystal structure. These inclusions reflect light in a way that forms a star-like pattern on the stone’s surface.

How are star sapphires cut to showcase their asterism?

Star sapphires are cut as cabochons, with a high dome that positions the star at the center of the stone. This cut enhances the visibility and symmetry of the asterism.

Are all star sapphires natural?

While most star sapphires are natural, some may undergo treatments to improve their color or asterism. Always verify the origin and treatment status with a trusted gemologist or retailer.

What is the most valuable color for a star sapphire?

The most valuable star sapphires typically have a vivid blue body color with a sharp and well-defined star. Other colors, such as pink, yellow, or black, can also be highly prized, depending on their quality and rarity.

Where are the most famous star sapphires found?

The most famous star sapphires, such as the Star of Adam, Star of India, and Star of Bombay, were discovered in Sri Lanka. Other sources include Myanmar, Thailand, and Australia.

Natural Sapphire for Sale in Our Gem Shop

We offer a wide range of natural sapphires, including star sapphires, that can be custom-made into exquisite jewelry pieces such as engagement rings, necklaces, stud earrings, bracelets, and pendants. Our skilled artisans ensure that every piece is tailored to your preferences, showcasing the timeless beauty of these extraordinary gemstones. Please contact us for a personalized quote.