Gemstone profile and identification guide
Blue Chalcedony
Blue chalcedony is a blue microcrystalline quartz variety valued for soft, uniform translucent colour.
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Overview
Blue chalcedony is a blue microcrystalline quartz variety valued for soft, uniform translucent colour.
Did you know? Many blue chalcedony stones in trade are marketed by locality names emphasizing hue.
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 Chalcedony
Scientific classification: Silicate (Chalcedony Quartz)
Hardness: 7 Mohs
Transparency: translucent
Lustre: waxy
Crystal system: Trigonal (microcrystalline aggregate)
Primary colour: Blue
Secondary colour: Grey Blue
Colour family: Blues
Uniform blue chalcedony texture and quartz hardness distinguish it from softer dyed alternatives.
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: 7 Mohs
Chemical composition: Silicon dioxide (SiO2)
Crystal system: Trigonal (microcrystalline aggregate)
Common locations: Namibia, Turkey, United States, India, Brazil
Learn more: Gem-A gemstone education resources.
Colour Variations
Translucent blue to grey-blue chalcedony with soft, even colour.
Optical effects: None specified in the current dataset.
Detailed Gemology
Mineral species: Quartz (chalcedony variety)
Mineral group: Quartz group
Chemical formula: Silicon dioxide (SiO2)
Mohs hardness: 7
Crystal system: Trigonal (microcrystalline aggregate)
Lustre: waxy
Transparency: translucent
Streak: White
Cleavage: None
Fracture: Conchoidal
Specific gravity: 2.58-2.64
Refractive index: 1.53-1.54
Optical phenomena: None typically diagnostic
Colour range: Blue, grey-blue, lavender-blue
Common inclusions: Subtle clouding, tiny fractures, silica growth textures
Geological environment: Silica-rich volcanic and sedimentary cavity fills
Principal mining regions: Namibia, Turkey, United States, India, Brazil
Important commercial sources: Commercial blue chalcedony is sourced notably from Namibia and Turkey with additional supply from several countries
Historical significance: Widely used in modern pastel-colour gemstone jewellery.
Common treatments: Dyeing can occur; verification is needed for intense saturated colours.
Synthetic or imitation forms: Dyed chalcedony and glass are common imitations.
Common look-alikes: Dyed agate, dyed quartzite, blue glass
Jewellery uses: Used in cabochons, beads, carvings, and ornamental jewellery.
Care recommendations: Quartz durability is good; avoid harsh impact on thin edges and carved details.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Blue Chalcedony.
Formation
Forms by low-temperature silica deposition in cavities and fractures.
Origin
Commercial blue chalcedony is sourced notably from Namibia and Turkey with additional supply from several countries
Uses
Best for: Used in cabochons, beads, carvings, and ornamental jewellery.
Ideal uses: Cabochons and beads that display even pastel colour.
Care
Quartz durability is good; avoid harsh impact on thin edges and carved details.
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
Blue Chalcedony FAQ
How can I identify Blue Chalcedony?
Compare hardness (7 Mohs), crystal system (Trigonal (microcrystalline aggregate)), colour profile, and lustre (waxy) with your sample. Then cross-check related gemstones listed above.
What colour range does Blue Chalcedony appear in?
Translucent blue to grey-blue chalcedony with soft, even colour.
Where is Blue Chalcedony commonly used?
Cabochons and beads that display even pastel colour.. 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.