Where is Star Ruby found?
Corundum (Al2O3) with asterism
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Open the appStar Ruby occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Star Ruby
Myanmar (Burma)
Historically significant source, particularly the Mogok Stone Tract, known for producing high-quality rubies, including star rubies, from marble deposits.
Sri Lanka (Ceylon)
A classic source for rubies and star rubies, primarily from alluvial deposits. Sri Lankan star rubies often exhibit a distinct purplish-red hue.
Thailand
Chanthaburi and Trat provinces were significant sources, often producing rubies with a brownish or purplish tint, some of which exhibit asterism.
Vietnam
Luc Yen and Quy Chau districts are known for producing rubies, including star rubies, from marble-hosted deposits.
Madagascar
Newer deposits have yielded significant quantities of rubies and star rubies, often from metamorphic terrains.
Tanzania
The Winza and Longido areas have produced rubies, some with asterism, from metamorphic rocks.
India
Various localities, particularly in Odisha and Karnataka, have produced rubies, including some star rubies, from metamorphic rocks and alluvial deposits.
Collecting tips
- Look for Cabochon Cuts. Star Rubies are almost always cut en cabochon (domed, unfaceted) to properly display the asterism. A faceted star ruby would not show the star effect.
- Single Light Source Test. To observe the star, illuminate the stone with a single, strong point light source (like a penlight or direct sunlight). The star should appear to move across the dome as the light source or stone is rotated.
- Examine Inclusions. Under magnification, the fine, needle-like rutile inclusions responsible for the asterism may be visible, often oriented in three sets at 60-degree angles to each other.
- Check for Natural vs. Synthetic. Natural star rubies often have natural inclusions, color zoning, and growth patterns. Synthetic star rubies (e.g., Verneuil process) typically show curved growth lines and gas bubbles, and their stars can appear too perfect or 'painted on'.
- Assess Star Quality. A high-quality star is sharp, centered, complete (all six rays visible), and moves smoothly across the dome. The intensity of the star should be strong against the body color of the ruby.
Quick Check
- Color:
- Red to reddish-purple
- Luster:
- Vitreous to adamantine
- Streak:
- White
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