Aquamarine, the transparent blue-to-blue-green variety of the mineral beryl (Be₃Al₂Si₆O₁₈), has served as the primary birthstone for March since the standardisation of the modern birthstone list in 1912. Recognised by both the American Gem Trade Association (AGTA) and Jewelers of America, it is one of the most commercially significant coloured gemstones in the world — prized for its cool, luminous colour, excellent clarity, and robust durability. Its association with the sea and with qualities of courage, calm, and mental clarity has made it a perennial choice for fine jewellery across centuries and cultures.

Historical and Symbolic Background

Before aquamarine's formal designation in 1912, bloodstone — a dark-green chalcedony flecked with red jasper — held the traditional March association in many European lapidary traditions. Bloodstone's connection to March derived largely from its longstanding Christian symbolism and its appearance in early gemstone calendars such as those compiled by the Polish gemologist Anselmus de Boodt in the early seventeenth century. Aquamarine gradually displaced bloodstone in popular and commercial practice throughout the nineteenth and early twentieth centuries, as the blue beryl became more widely available from Brazilian deposits and as consumer preference shifted toward transparent, faceted gems.

The name derives from the Latin aqua marina, meaning "water of the sea," a reference that ancient and Renaissance lapidaries took quite literally: the stone was believed to protect sailors and guarantee safe passage across open water. Roman writers described it as sacred to Neptune. These maritime associations persist in contemporary symbolic usage, where aquamarine is linked to tranquillity, clear communication, and emotional resilience.

Gemmological Properties

As a member of the beryl group, aquamarine shares the hexagonal crystal system and the characteristic hardness of 7.5 to 8 on the Mohs scale, making it well suited to everyday wear in rings, pendants, and bracelets. Its colour is produced by trace amounts of ferrous iron (Fe²⁺); the more intensely saturated the blue, the more desirable the stone in the trade. Refractive indices fall in the range of approximately 1.577 to 1.583, with a birefringence of 0.005 to 0.009 — low enough that doubling of back facets is not a practical concern. Specific gravity is typically 2.68 to 2.74.

Aquamarine is strongly pleochroic, displaying blue and nearly colourless tones when viewed along different crystallographic axes. Cutters orient rough carefully to maximise the blue face-up appearance. The gem is generally free of inclusions visible to the naked eye — a characteristic that distinguishes it from its beryl relatives emerald and heliodor, both of which are far more commonly included.

Principal Origins

Brazil is by far the world's dominant source, with the states of Minas Gerais, Espírito Santo, and Bahia producing the great majority of commercial and fine-quality material. The most celebrated single locality is Santa Maria de Itabira in Minas Gerais, whose intensely saturated stones gave rise to the trade designation Santa Maria — a term now applied loosely to any deeply coloured aquamarine regardless of origin. Other significant sources include:

• Nigeria and Mozambique, which have produced fine, deeply saturated material sometimes marketed as Santa Maria Africana.
• Pakistan and Afghanistan, particularly the Shigar Valley and Kunar province, sources of exceptional crystal specimens as well as facetable rough.
• Madagascar, a consistent producer of clean, well-coloured material.
• Russia (the Ural Mountains), historically important and the source of some notable collector specimens.

Treatment

The overwhelming majority of aquamarine on the market has been heat-treated. Many beryl crystals occur naturally in a greenish-blue colour caused by a combination of Fe²⁺ and Fe³⁺ ions; gentle heating to temperatures between approximately 400 °C and 450 °C reduces the Fe³⁺ component and shifts the colour toward a purer, more commercially desirable blue. This treatment is stable, undetectable by standard gemmological testing, and universally accepted in the trade. Disclosure is not typically required because the treatment is considered standard practice, though reputable laboratories such as the GIA will note colour characteristics in their reports.

In the Trade and as a Gift

Aquamarine is available in a wide range of sizes, from small calibrated stones for mass-market jewellery to fine faceted gems exceeding 100 carats for collector and auction pieces. The most prized colour is a rich, medium-dark pure blue with no greenish secondary hue, though lighter, more transparent stones remain popular for their ethereal, water-like appearance. The gem is also the traditional gift for a nineteenth wedding anniversary.

As a March birthstone, aquamarine occupies a particularly accessible position in the coloured-gemstone market: it is durable enough for daily wear, available in sizes and qualities suited to nearly every price point, and possessed of a colour universally regarded as flattering. These qualities, combined with its long symbolic history, ensure its continued prominence both as a birthstone and as a fine jewellery gem in its own right.

Further Reading

• GIA Gem Encyclopedia: Aquamarine
• AGTA Gemstone Encyclopedia: Aquamarine