Aquamarine
Last updated: April 2026
Aquamarine is the light blue to greenish-blue variety of beryl.
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
Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.
Through the refractometer
Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.
Related: Beryl Varieties
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.
Loupewise Pro includes a two-phase natural vs. synthetic testing protocol for Aquamarine.
Common Simulants
- Blue topaz: Biaxial positive DR; higher SG (3.53); perfect basal cleavage; RI 1.609–1.643.
- 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)
Related Comparisons
Measurement Guides
Identifying an aquamarine? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Aquamarine is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →