Aquamarine

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Aquamarine has a specific gravity of 2.72 and a refractive index of 1.577–1.583, with a Mohs hardness of 7.5–8.0. It is uniaxial −.

Physical & Optical Properties

RI Range1.577–1.583

SG Range2.68–2.78

SG Typical2.72

Hardness (Mohs)7.5–8

Crystal SystemHexagonal

Optic CharacterDR Uniaxial (−)

Birefringence0.006

Dispersion0.014

Fluorescence LWInert

Fluorescence SWInert

Chelsea FilterInert

PleochroismWeak

ColorsBlue Violet, Green

SpeciesBeryl

Key Differentiators

Low RI and SG
Dichroism of colorless and blue
Often eye-clean

Natural vs. Synthetic

Synthetic aquamarine is commercially available (Hydrothermal (rare commercially)). Distinguishing natural from synthetic typically requires microscopic examination of internal features.

Microscopy — inclusions: Parallel elongated negative crystal inclusions, mica flakes (biotite), fingerprint healed fractures, long irregular liquid-filled growth tubes. Synthetic: Seed plate (faint straight rectangular boundary). Irregular void two-phase inclusions in distinct planes. Parallel growth tubes more uniform and hollow than natural. Absence of elongated negative crystal and mica inclusions.
Heat treatment (note): Virtually all commercial aquamarine is heat-treated to remove green/yellow. Undetectable by standard instruments — assume heated. Synthetic: N/A — heat treatment applies to natural material only.

GemID Pro includes a two-phase natural vs. synthetic testing protocol for Aquamarine.

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Common Simulants

Blue topaz: Biaxial positive DR; higher SG (3.53); perfect basal cleavage; RI 1.619–1.627.
Glass: Isotropic; gas bubbles or swirl marks under loupe; no dichroism; SG typically 2.3–4.5 depending on type.
Synthetic blue spinel: Isotropic (SR); RI ~1.727; may show anomalous double refraction under polariscope; Chelsea filter variable.

Commonly Confused With

Commonly confused with: Topaz, Glass, Synthetic Spinel, Fluorite, Indicolite, Paraiba Tourmaline.

Treatments

Heat Treatment (green → blue)

Price Context

Natural — low ($/ct)$50

Natural — high ($/ct)$400

NotePer carat; deep Santa Maria blue commands top prices; Brazilian material preferred

Synthetic — low ($/ct)$5

Synthetic — high ($/ct)$30

Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.

Related Comparisons

Measurement Guides

Identifying an aquamarine? GemID walks through these tests in order — RI, SG, fluorescence, and more.

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Studying for the GIA, FGA, or FEEG practical? Aquamarine is one of the 130 species in GemID’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.

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