Aquamarine Gemstones – Properties, Origins, Treatments and Buying Guide

Aquamarine is one of the world’s most admired blue gemstones, celebrated for its calming ocean-like colour, excellent clarity and elegant brilliance. A member of the beryl family, aquamarine has been prized for centuries for both its beauty and durability, making it a favourite in fine jewellery.

In this guide we explore aquamarine from a professional gemmological and commercial perspective, covering its mineral composition, optical properties, durability, treatments, origins and how to identify high-quality stones.

What Is Aquamarine?

Aquamarine is the blue to blue-green variety of the mineral beryl, the same mineral family as emerald, morganite and heliodor. Its name is derived from the Latin “aqua marina”, meaning “water of the sea”, referencing its clear, ocean-like colour.

Aquamarine forms in granitic pegmatites and hydrothermal veins and is valued for its excellent transparency, crisp brilliance and superior durability compared to many other coloured gemstones.

Aquamarine has the chemical formula:

Be₃Al₂Si₆O₁₈

This means it is composed primarily of:

• Beryllium
• Aluminium
• Silicon
• Oxygen

The blue colour of aquamarine is caused by trace amounts of iron within the crystal structure.

• Low iron = pale blue
• Higher iron = deeper blue or blue-green

The most valuable aquamarines show a clear, saturated blue with minimal green or grey tones.

Aquamarine belongs to the beryl family, a group of silicate minerals that also includes emerald and morganite.

Its crystal system is hexagonal, which produces long prismatic crystals with excellent clarity and structural strength.

This crystal structure contributes to aquamarine’s durability and its suitability for a wide range of jewellery designs.

Aquamarine possesses excellent optical characteristics that make it highly desirable in fine jewellery.

Lustre
Aquamarine displays a bright vitreous (glassy) lustre, giving well-cut stones exceptional brilliance.

Transparency
Gem-quality aquamarine is transparent and highly valued for its clarity.

Refractive index
1.57 – 1.58
Aquamarine has a clean brilliance with subtle sparkle and excellent light return.

Specific Gravity
2.68 – 2.74
Aquamarine is slightly lighter than many gemstones such as sapphire and ruby, contributing to its comfortable wear while retaining excellent heft for a premium feel.

Aquamarine occurs in a range of blue shades:

• Pale sky blue
• Aqua blue
• Greenish blue
• Deep ocean blue (most valuable)

The finest aquamarines display a strong, even blue with excellent transparency and no grey or green undertone.

Aquamarine has a Mohs hardness of 7.5 to 8, making it significantly more durable than many coloured gemstones.

It offers:

• Good toughness
• Excellent resistance to scratching
• Suitability for rings, earrings and daily wear

With proper care, aquamarine jewellery can last generations.

Aquamarine is commonly heat treated to remove green or yellow tones and enhance its blue colour.

Common treatments:

• Heat treatment (stable and accepted)

Rare:

• Fracture filling (low-quality stones only)

Heat treatment is permanent and widely accepted within the gemstone trade.

Aquamarine is relatively easy to care for.

Avoid:

• Strong impacts
• Harsh chemicals
• Prolonged heat exposure

Safe cleaning:

• Warm soapy water
• Soft brush
• Soft cloth drying

Store separately from harder gemstones to avoid scratching.

Major aquamarine sources include:

• Brazil (world’s largest producer)
• Madagascar
• Nigeria
• Pakistan
• Mozambique
• Zambia
• Sri Lanka

Brazilian aquamarine is particularly prized for its clarity and colour consistency.