Gemstone profile and identification guide
Star Sapphire
Star Sapphire profile is under factual gemological review. Properties shown here are provisional unless marked as verified.
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Overview
Star Sapphire profile is under factual gemological review. Properties shown here are provisional unless marked as verified.
Did you know? The star effect appears only when needle-like inclusions are aligned well enough to reflect light in intersecting bands.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Identification
Name: Star Sapphire
Scientific classification: Oxide (Corundum Variety)
Hardness: 9 Mohs
Transparency: transparent
Lustre: vitreous to adamantine
Crystal system: Trigonal
Primary colour: Blue
Secondary colour: Sapphire Blue
Colour family: Blues & Cyans
Start with hardness, lustre, and transparency: Star Sapphire is recorded here as 9 on the Mohs scale with vitreous lustre and transparent transparency. Its asterism is a strong clue and should be checked under changing light rather than judged from a single still view. Useful side-by-side comparisons include Sapphire, Ruby, Spinel.
Verification Status
Status: verified-family-derived
Reference priority: GIA, Gem-A, Mindat, International Gem Society
Core identity fields inherited from verified parent profile: sapphire.
Star sapphire profile inherits sapphire core identity and asterism effect.
Variety-level locality and treatment specifics can differ and should be reviewed before publication-grade claims.
Physical Properties
Hardness category: very hard
Hardness value: 9 Mohs
Chemical composition: Aluminum oxide (Al2O3)
Crystal system: Trigonal
Common locations: Sri Lanka, Madagascar, Australia, Myanmar, Kashmir (historic India)
Learn more: Gem-A gemstone education resources.
Colour Variations
Star Sapphire sits in the blues & cyans grouping here, usually reading first as blue with sapphire blue appearing as a secondary note or modifier. Some specimens also show asterism, which can alter the way the colour is perceived under changing light.
Optical effects: Asterism
Detailed Gemology
Mineral species: Corundum (sapphire variety)
Mineral group: Corundum
Chemical formula: Aluminum oxide (Al2O3)
Mohs hardness: 9
Crystal system: Trigonal
Lustre: vitreous to adamantine
Transparency: transparent
Streak: White
Cleavage: No true cleavage; parting may occur
Fracture: Conchoidal to uneven
Specific gravity: 3.99-4.01
Refractive index: 1.76-1.77
Optical phenomena: Asterism
Colour range: Blue, Sapphire Blue, Pink
Common inclusions: Rutile silk, crystal inclusions, and healed fractures
Geological environment: Star Sapphire occurs in Metamorphic marbles and igneous/metamorphic deposits with alluvial concentrations. Its Trigonal structure reflects the pressure-temperature conditions of those host rocks, with notable occurrences in Sri Lanka, Madagascar, Australia, Myanmar, Kashmir (historic India).
Principal mining regions: Sri Lanka, Madagascar, Australia, Myanmar, Kashmir (historic India)
Important commercial sources: Commercial sapphire is sourced chiefly from Sri Lanka and Madagascar; Australia and Myanmar are also important
Historical significance: Ruby and sapphire are among the most historically significant and durable gem species.
Common treatments: Heat treatment is common; diffusion and fracture-filling treatments may occur and require disclosure.
Synthetic or imitation forms: Synthetic corundum (Verneuil, flux, hydrothermal) and glass imitations exist.
Common look-alikes: sapphire, ruby, spinel
Jewellery uses: Star Sapphire is used chiefly for Well suited to daily-wear jewellery, especially when cut and set to show colour or brilliance cleanly.. In the trade it is commonly fashioned as faceted stones, calibrated cuts, and higher-clarity collector pieces, with Mohs hardness 9 guiding suitable jewellery applications.
Care recommendations: Star Sapphire should be cleaned with lukewarm water, mild soap, and a soft brush. At Mohs 9 in the Trigonal system, avoid steam cleaners, harsh chemicals, and high-impact wear. Protect cleavage directions from sharp knocks during wear and setting.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Star Sapphire.
Formation
Star Sapphire is a Corundum (sapphire variety) material with chemistry Aluminum oxide (Al2O3). It develops in Metamorphic marbles and igneous/metamorphic deposits with alluvial concentrations, and economically significant production is associated with Sri Lanka, Madagascar, Australia, Myanmar, Kashmir (historic India).
Origin
Commercial sapphire is sourced chiefly from Sri Lanka and Madagascar; Australia and Myanmar are also important
Uses
Best for: Star Sapphire is used chiefly for Well suited to daily-wear jewellery, especially when cut and set to show colour or brilliance cleanly.. In the trade it is commonly fashioned as faceted stones, calibrated cuts, and higher-clarity collector pieces, with Mohs hardness 9 guiding suitable jewellery applications.
Ideal uses: Well suited to daily-wear jewellery, especially when cut and set to show colour or brilliance cleanly.
Care
Star Sapphire should be cleaned with lukewarm water, mild soap, and a soft brush. At Mohs 9 in the Trigonal system, avoid steam cleaners, harsh chemicals, and high-impact wear. Protect cleavage directions from sharp knocks during wear and setting.
Need another candidate? Use advanced gemstone search or return to the identification guide.
Related gemstones by colour
Related gemstones by hardness
Gemstones from the same mineral family
Commonly confused gemstones
Star Sapphire FAQ
How can I identify Star Sapphire?
Compare hardness (9 Mohs), crystal system (Trigonal), colour profile, and lustre (vitreous to adamantine) with your sample. Then cross-check related gemstones listed above.
What colour range does Star Sapphire appear in?
Star Sapphire sits in the blues & cyans grouping here, usually reading first as blue with sapphire blue appearing as a secondary note or modifier. Some specimens also show asterism, which can alter the way the colour is perceived under changing light.
Where is Star Sapphire commonly used?
Well suited to daily-wear jewellery, especially when cut and set to show colour or brilliance cleanly.. For maintenance, follow the care guidance in this profile.
Scientific References
GIA: general gemstone identity (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: sapphire.
Gem-A: gemological education and terminology (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: sapphire.
Mindat: mineral species and locality index (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: sapphire.
International Gem Society: collector-facing gem reference (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: sapphire.