Gemstone profile and identification guide
Durability is part of the appeal of London Blue Topaz, not merely a technical footnote. Jewellers who need dependable wear resistance often come to it for different reasons, but identification still comes back to blue body colour, 8 Mohs hardness, and vitreous lustre.
Durability is part of the appeal of London Blue Topaz, not merely a technical footnote. Jewellers who need dependable wear resistance often come to it for different reasons, but identification still comes back to blue body colour, 8 Mohs hardness, and vitreous lustre.
Did you know? London Blue Topaz is commonly associated with material from Brazil, though the broader trade may draw on multiple localities.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Name: London Blue Topaz
Scientific classification: Nesosilicate (Topaz)
Hardness: 8 Mohs
Transparency: transparent
Lustre: vitreous
Crystal system: Orthorhombic
Primary colour: Blue
Secondary colour: Not specified
Colour family: Blues & Cyans
When separating London Blue Topaz from similar-looking stones, pay attention to the combination of 8 Mohs hardness, vitreous lustre, and orthorhombic crystal structure. Colour on its own is not enough; use hardness and lustre alongside hue to rule out obvious lookalikes. Useful side-by-side comparisons include Topaz, Moonstone, Peridot.
Status: verified-family-derived
Reference priority: GIA, Gem-A, Mindat, International Gem Society
Core identity fields inherited from verified parent profile: topaz.
London blue topaz variety profile inherits topaz core identity fields.
Variety-level locality and treatment specifics can differ and should be reviewed before publication-grade claims.
Hardness category: hard
Hardness value: 8 Mohs
Chemical composition: Aluminum fluorine hydroxyl silicate [Al2SiO4(F,OH)2]
Crystal system: Orthorhombic
Common locations: Brazil (Minas Gerais), Pakistan, Russia, Nigeria, Sri Lanka
Learn more: Gem-A gemstone education resources.
London Blue Topaz is listed in the blues & cyans grouping, with blue as the dominant body colour.
Optical effects: None specified in the current dataset.
Mineral species: Topaz
Mineral group: Topaz group
Chemical formula: Aluminum fluorine hydroxyl silicate [Al2SiO4(F,OH)2]
Mohs hardness: 8
Crystal system: Orthorhombic
Lustre: vitreous
Transparency: transparent
Streak: White
Cleavage: Perfect basal cleavage
Fracture: Subconchoidal to uneven
Specific gravity: 3.49-3.57
Refractive index: 1.61-1.64
Optical phenomena: None commonly reported
Colour range: Blue
Common inclusions: Liquid inclusions, fractures, and growth zoning
Geological environment: London Blue Topaz occurs in Granitic pegmatites, rhyolitic cavities, and hydrothermal environments. Its Orthorhombic structure reflects the pressure-temperature conditions of those host rocks, with notable occurrences in Brazil (Minas Gerais), Pakistan, Russia, Nigeria, Sri Lanka.
Principal mining regions: Brazil (Minas Gerais), Pakistan, Russia, Nigeria, Sri Lanka
Important commercial sources: Brazil is the principal producer of gem topaz, with additional sources in Pakistan, Russia, and Nigeria
Historical significance: Topaz has been used in jewelry for centuries and remains a major faceted gemstone species.
Common treatments: Irradiation and heat are common for blue topaz; coatings are used for products such as mystic topaz.
Synthetic or imitation forms: Synthetic substitutes and glass imitations are available in the market.
Common look-alikes: topaz, moonstone, peridot
Jewellery uses: London Blue Topaz is used chiefly for Particularly useful where durability matters alongside colour, clarity, or optical performance.. In the trade it is commonly fashioned as faceted stones, calibrated cuts, and higher-clarity collector pieces, with Mohs hardness 8 guiding suitable jewellery applications.
Care recommendations: London Blue Topaz should be cleaned with lukewarm water, mild soap, and a soft brush. At Mohs 8 in the Orthorhombic 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 London Blue Topaz.
London Blue Topaz is a Topaz material with chemistry Aluminum fluorine hydroxyl silicate [Al2SiO4(F,OH)2]. It develops in Granitic pegmatites, rhyolitic cavities, and hydrothermal environments, and economically significant production is associated with Brazil (Minas Gerais), Pakistan, Russia, Nigeria, Sri Lanka.
Brazil is the principal producer of gem topaz, with additional sources in Pakistan, Russia, and Nigeria
Best for: London Blue Topaz is used chiefly for Particularly useful where durability matters alongside colour, clarity, or optical performance.. In the trade it is commonly fashioned as faceted stones, calibrated cuts, and higher-clarity collector pieces, with Mohs hardness 8 guiding suitable jewellery applications.
Ideal uses: Particularly useful where durability matters alongside colour, clarity, or optical performance.
London Blue Topaz should be cleaned with lukewarm water, mild soap, and a soft brush. At Mohs 8 in the Orthorhombic 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.
Compare hardness (8 Mohs), crystal system (Orthorhombic), colour profile, and lustre (vitreous) with your sample. Then cross-check related gemstones listed above.
London Blue Topaz is listed in the blues & cyans grouping, with blue as the dominant body colour.
Particularly useful where durability matters alongside colour, clarity, or optical performance.. For maintenance, follow the care guidance in this profile.
GIA: general gemstone identity (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: topaz.
Gem-A: gemological education and terminology (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: topaz.
Mindat: mineral species and locality index (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: topaz.
International Gem Society: collector-facing gem reference (reviewed) - Reviewed as a variety profile derived from verified parent gemstone: topaz.
