Gemstone profile and identification guide
Blue Moonstone
Blue moonstone is a trade term for moonstone-type feldspar showing a blue sheen effect.
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Overview
Blue moonstone is a trade term for moonstone-type feldspar showing a blue sheen effect.
Did you know? In trade, some blue moonstone is actually labradorite sold under moonstone-related names.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Identification
Name: Blue Moonstone
Scientific classification: Feldspar (Moonstone Trade Variety)
Hardness: 6 Mohs
Transparency: translucent
Lustre: vitreous to pearly
Crystal system: Monoclinic/triclinic feldspar intergrowth context
Primary colour: White
Secondary colour: Blue Sheen
Colour family: Whites & Neutrals
Blue sheen, feldspar SG/RI range, and cleavage behavior are key diagnostic indicators.
Verification Status
Status: verified-core-fields
Reference priority: GIA, Gem-A, Mindat, International Gem Society
Core identity, locality, and physical-property fields reviewed against standard gemological references.
Values are reported as practical gemological ranges where appropriate.
Physical Properties
Hardness category: hard
Hardness value: 6 Mohs
Chemical composition: (K,Na)AlSi3O8 feldspar intergrowth (orthoclase/albite; some trade material is labradorite)
Crystal system: Monoclinic/triclinic feldspar intergrowth context
Common locations: Sri Lanka, India, Madagascar, Tanzania, Myanmar
Learn more: Gem-A gemstone education resources.
Colour Variations
Colorless to white feldspar body with blue adularescent or labradorescent sheen depending on material.
Optical effects: Adularescence
Detailed Gemology
Mineral species: Feldspar intergrowth moonstone-type material
Mineral group: Feldspar group
Chemical formula: (K,Na)AlSi3O8 feldspar intergrowth (orthoclase/albite; some trade material is labradorite)
Mohs hardness: 6
Crystal system: Monoclinic/triclinic feldspar intergrowth context
Lustre: vitreous to pearly
Transparency: translucent
Streak: White
Cleavage: Perfect in two directions
Fracture: Uneven
Specific gravity: 2.55-2.62
Refractive index: 1.518-1.526 (orthoclase-rich); variable for labradorite-related trade material
Optical phenomena: Adularescence (or schiller/labradorescence in some trade material)
Colour range: Colorless to white with blue sheen
Common inclusions: Lamellae, veils, cleavage traces
Geological environment: Pegmatitic and plutonic feldspar-bearing environments
Principal mining regions: Sri Lanka, India, Madagascar, Tanzania, Myanmar
Important commercial sources: Commercial blue-sheen moonstone is sourced mainly from Sri Lanka, India, and Madagascar
Historical significance: A long-standing jewellery material in moonstone categories.
Common treatments: Coating and filling can occur in low-grade products.
Synthetic or imitation forms: Glass and synthetic opalite products imitate blue sheen.
Common look-alikes: Labradorite, opalite glass, synthetic sheen materials
Jewellery uses: Used in cabochons and jewellery emphasizing blue sheen.
Care recommendations: Moderate hardness with feldspar cleavage; avoid impact and ultrasonic cleaning.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Blue Moonstone.
Formation
Optical sheen develops from fine-scale feldspar intergrowth structures formed during cooling and exsolution.
Origin
Commercial blue-sheen moonstone is sourced mainly from Sri Lanka, India, and Madagascar
Uses
Best for: Used in cabochons and jewellery emphasizing blue sheen.
Ideal uses: Cabochons in protected settings to maximize surface sheen.
Care
Moderate hardness with feldspar cleavage; avoid impact and ultrasonic cleaning.
Need another candidate? Use advanced gemstone search or return to the identification guide.
Related gemstones by colour
Related gemstones by hardness
Commonly confused gemstones
Blue Moonstone FAQ
How can I identify Blue Moonstone?
Compare hardness (6 Mohs), crystal system (Monoclinic/triclinic feldspar intergrowth context), colour profile, and lustre (vitreous to pearly) with your sample. Then cross-check related gemstones listed above.
What colour range does Blue Moonstone appear in?
Colorless to white feldspar body with blue adularescent or labradorescent sheen depending on material.
Where is Blue Moonstone commonly used?
Cabochons in protected settings to maximize surface sheen.. For maintenance, follow the care guidance in this profile.
Scientific References
GIA: general gemstone identity (reviewed) - Batch 03 factual verification pass.
Gem-A: gemological terminology and testing references (reviewed) - Batch 03 factual verification pass.
Mindat: mineral species and principal localities (reviewed) - Batch 03 factual verification pass.
International Gem Society: gem trade context and treatment overview (reviewed) - Batch 03 factual verification pass.