Topaz is a hard silicate mineral that naturally occurs as colorless, pale yellow, or brown. It scores an 8 on the Mohs hardness scale, making it very durable for rings and daily jewelry.

Cornerstone gemstone profile

Topaz

A distinct silicate mineral used as a gem

Species
Topaz
Formula
Al₂(F,OH)₂SiO₄[1]
Mohs
8[1]
Refractive index
1.619–1.627[1]

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01

Definition

What is Topaz?

Topaz is a mineral species used as a gem in several colors. Detailed reference values are pending editorial review. [1]

02

At a glance

Gemological properties

Measured values and species-level properties are linked to their evidence. “Pending” means the value has not cleared review.

1public references
Scientific and gemological properties of Topaz
GemstoneTopazMineral speciesTopaz
Mineral groupSilicatesFamilyPending verification
Chemical formulaAl₂(F,OH)₂SiO₄[1]Crystal systemPending verification
Mohs hardnessMohs hardnessA comparative scale of scratch resistance from 1 to 10; it does not measure toughness.Learn more8[1]Specific gravitySpecific gravityThe ratio of a material’s density to the density of water under defined conditions.Learn more3.53[1]
Refractive indexRefractive indexA measurement describing how light changes speed and direction as it enters a material.Learn more1.619–1.627[1]BirefringenceBirefringenceThe numerical difference between a doubly refractive material’s principal refractive indices.Learn more0.008–0.01[1]
Optic characterPending verificationDispersionDispersionThe separation of white light into spectral colors because refractive index varies with wavelength.Learn morePending verification
Primary colorMulticolorPleochroismPleochroismDifferent body colors seen in some anisotropic gems when viewed along different crystallographic directions.Learn morePending verification
LusterLusterThe character of light reflected from a material’s surface.Learn morePending verificationTransparencyPending verification
CleavageCleavageA mineral’s tendency to split along specific crystallographic planes.Learn morePending verificationFracturePending verification
TenacityTenacityA material’s response to bending, breaking, crushing, or tearing.Learn morePending verificationFluorescencePending verification
StreakPending verificationAvailabilityNatural · Laboratory-grown
Jewelry suitabilityPending verification

Scope note: some physical properties describe corundum as a mineral species; ruby-specific claims are identified separately in the citations.

REF

Evidence

References & further reading

Citation numbers are deduplicated across properties, claims, sections, structured modules, treatments, inclusions, FAQs, and related educational records.

  1. [1]
    Topaz Gemstone Overview.

    Gemological Institute of America

    View source
Written byThe Gem Index Editorial Team
Reviewed byReview pending
Last reviewedPending
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