Aquamarine

Aquamarine is the blue to blue-green variety of the mineral beryl, the same species that produces emerald. Its name comes from the Latin for 'seawater,' reflecting its calm sky-blue to sea-green color, which is caused by traces of iron.

It forms in the hexagonal crystal system, often as long, well-formed six-sided prismatic crystals that can be large and remarkably clean compared with emerald. Most gem aquamarine is pale; deeper, more saturated blues are the most valued.

Durable (Mohs 7.5-8), transparent, and available in large sizes, aquamarine is a popular and relatively affordable gemstone and the birthstone for March.

Aquamarine forms chiefly in granitic pegmatites — coarse-grained igneous rocks where slow crystallization from water- and beryllium-rich residual magma allows large, clean crystals to grow in cavities.

It also occurs in some hydrothermal veins and metamorphic environments. The blue color is produced by ferrous (Fe2+) iron; gentle heat treatment is commonly used to remove greenish-yellow tones and enhance pure blue.

Major sources include Brazil (Minas Gerais), Pakistan, Nigeria, Madagascar, Mozambique, and the famous gem pockets of Colorado's Mount Antero in the USA.

Aquamarine is recognized by its pale, even sky-blue to sea-green color, hardness of 7.5-8, vitreous luster, and excellent transparency, often in elongated hexagonal crystals with flat striated faces. It has a white streak and weak pleochroism (color shifts blue to near-colorless as the stone is turned).

It is typically very clean, with fewer inclusions than emerald.

Look-alikes: Blue topaz is similar but is denser and has different cleavage and pleochroism; treated blue topaz is often more intensely blue. Blue zircon is more brilliant with strong double refraction. Glass imitations lack pleochroism and crystalline inclusions. Pale color plus great clarity and beryl crystal form point to aquamarine.

Aquamarine is valued almost exclusively as a gemstone, faceted into rings, pendants, and earrings, and prized for large, clean stones that cut beautifully. Deeply saturated 'Santa Maria' blues fetch the highest prices.

Its hardness and lack of cleavage sensitivity (compared to emerald) make it durable for everyday jewelry. Large crystals are also collected as mineral specimens.

As the March birthstone, aquamarine symbolizes calm, clarity, and the sea, and has long been considered a talisman for sailors. In metaphysical practice it is linked to soothing communication and emotional balance.