Star Ruby

Physical Properties

Hardness: 9.0; Color: Pinkish-red to deep red; Luster: Adamantine to vitreous; Crystal system: Trigonal; Features an 'asterism' (6-rayed star) caused by needle-like rutile inclusions.

Formation & Geological History

Formed in metamorphic or igneous environments, particularly marble or basalt. The 'star' effect requires millions of years of gradual cooling to allow rutile needles to align perfectly.

Uses & Applications

Primarily used in high-end jewelry (cabochon cut) and as a valuable collector's gemstone.

Geological Facts

Star gems like this ruby are usually cut into a cabochon (smooth, rounded shape) rather than faceted to ensure the star is visible. It is the birthstone for July.

Field Identification & Locations

Identify by a 6-rayed star appearing under a single point of light that moves as the stone is tilted. Generally found in Myanmar, Sri Lanka, and Africa.

Identified on: 4/15/2026

Mode: Standard