Crystal guide
How to Identify Aquamarine
Be₃Al₂Si₆O₁₈ (Beryl)
Aquamarine is the sea-blue variety of beryl (Be₃Al₂Si₆O₁₈) forming hexagonal prisms. Identify it by pale blue-green color, hexagonal crystal habit, Mohs 7.5–8, vitreous luster, and watery clarity that gave the March birthstone its name.
About Aquamarine
Aquamarine is the sea-blue variety of beryl (Be₃Al₂Si₆O₁₈) forming hexagonal prisms. Identify it by pale blue-green color, hexagonal crystal habit, Mohs 7.5–8, vitreous luster, and watery clarity that gave the March birthstone its name.
Aquamarine is filed under crystals in the RockScan directory. Composition: Beryllium aluminum silicate. It forms via pegmatites and hydrothermal veins. Typical occurrence: Brazil, Pakistan, Madagascar, USA (Colorado). For the broader method, see how to identify rock types.
Aquamarine properties
| Mohs hardness | 7.5–8 |
|---|---|
| Class | crystal |
| Scientific name | Be₃Al₂Si₆O₁₈ (Beryl) |
| Color | Pale to medium blue-green |
| Luster | Vitreous |
| Crystal system / texture | Hexagonal |
| Composition | Beryllium aluminum silicate |
| Formation | Pegmatites and hydrothermal veins |
| Occurrence | Brazil, Pakistan, Madagascar, USA (Colorado) |
How to identify Aquamarine
- Pale sea-blue to blue-green in hexagonal prisms.
- Mohs 7.5–8; scratches quartz, resists a knife fully.
- Hexagonal habit with flat terminations; no bubbles (rules out glass).
Lookalikes to rule out
- Blue topaz: Blue topaz reaches Mohs 8 with perfect basal cleavage; aquamarine is beryl (7.5–8) with hexagonal prisms and weaker cleavage.
- Blue glass: Glass shows bubbles and mold seams with even color; aquamarine shows hexagonal growth, zoning, and no bubbles.
- Blue chalcedony: Chalcedony is massive microquartz (~7) with waxy translucency; aquamarine forms distinct hexagonal crystals.
Photo tips for Aquamarine ID
- Shoot hexagonal prism faces and terminations straight-on; habit is the diagnosis.
- Use white background for pale stones — aquamarine washes out on blue grounds.
- Show color zoning along the crystal length; natural aquas zone from clear to blue.
Snap one specimen in natural light, then open the result in the online studio or the rock identifier app.
Aquamarine FAQ
How do you identify aquamarine?
Look for pale blue hexagonal beryl crystals at Mohs 7.5–8. Blue topaz has basal cleavage; glass has bubbles.
Aquamarine vs blue topaz?
Topaz hits Mohs 8 with a perfect cleavage plane; aquamarine is hexagonal beryl with subtler cleavage and watery zoning.
Is aquamarine related to emerald?
Yes — both are beryl. Chromium makes emerald green; iron makes aquamarine blue.
How to identify aquamarine
Pale-blue stones get mislabeled between aquamarine, topaz, and glass. Hexagonal habit plus hardness orders them:
- Sea-blue tone: pale watery blue to blue-green; deep London-blue usually means treated topaz.
- Hexagonal prisms: six-sided crystals with flat or etched terminations — glass never grows these.
- Hardness 7.5–8: scratches quartz easily; chalcedony (~7) cannot scratch it back.
- Zoning: natural color banding along the crystal length beats dyed-glass uniformity.
- Photo confirm: prism-face shots on white plus a zoning view, then RockScan against topaz and glass.
Aquamarine vs blue topaz vs glass vs blue chalcedony
- Blue topaz: Mohs 8 with a perfect basal cleavage plane; aquamarine is hexagonal beryl.
- Blue glass: bubbles, mold seams, and swirl marks with no crystal faces.
- Blue chalcedony: massive waxy microquartz with no hexagonal prisms.
Photo tips for aquamarine prisms
White grounds keep pale blue honest; shoot prism faces, terminations, and lengthwise zoning. Compare topaz, quartz, and tourmaline guides, then confirm in the online studio or rock identifier app.
Related crystals to compare
Browse all: rocks · minerals · crystals · directory · what rock is this · rock vs mineral vs crystal. Confirm with the online studio or rock identifier app.