Black Star Sapphire Oval Cabochon

The eye-catching six-ray star of this oval black star sapphire cabochon and its deep-black color make it an ideal choice for a centerpiece design such as a pendant. Partner these designs with complementary-color cabs to create matched sets with bracelets or earrings, or us it to create more complex, multi-stone necklace designs. Star sapphire is named for its distinctive six-ray star, visible under a single overhead light source, and occurs in black, blue and red corundum (red varieties are known as "star rubies"). The star is the result of intersecting needle-like inclusions within the gemstone that follow the underlying crystal structure and reflect light in a different direction than does the surrounding mineral, creating the appearance of the star. In a black sapphire, the inclusions are hematite, a mineral composed primarily of ferrous oxide. This star effect is known as “asterism.” The value of a given gemstone is based on the symmetry, orientation, definition, color and clarity of the star.

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Gemstone type: Sapphire
Stone shape: Oval
Stone size: 10 x 8mm, 6 x 4mm, 7 x 5mm, 8 x 6mm
Stone type: Natural
Color: Black
Enhancement: None (N)
Mohs hardness: 9
Refractive index: 1.762–1.77
Specific gravity: 3.96–4.05
Cutting center: Thailand, Taiwan