Aquamarine

The name aquamarine comes from Latin "aqua marina" — seawater. Roman fishermen believed a stone they wore would bring safety at sea. Legend holds that treasure troves on the ocean floor are filled with aquamarine.

Brazil became the most important source of aquamarine after the discovery in 1811 near Teofilo Otoni (Minas Gerais). A 7-kilogram crystal was found — per GIA CS the first large crystal ever recorded. In 1910, the then-largest crystal was discovered in Minas Gerais: 110 kg, 48 cm long and 19 cm in diameter, so transparent that printed text could be read through it.

Mozambique has in recent decades become an equal source of intensely blue stones — "Santa Maria Africana" blue from Mozambique is comparable to the original Brazilian standard.

Santa Maria azul: The most prized aquamarine color is "Santa Maria azul" (intense blue to bluish) — the name comes from the Brazilian mine Santa Maria de Itabira. Similarly intense stones are now called "Santa Maria Africana" and come from Mozambique.

Dom Pedro: The world's largest faceted aquamarine (13,905 ct, 60 cm high obelisk) was carved by German artist Bernd Munsteiner from a single Brazilian crystal — displayed at the Smithsonian National Museum of Natural History in Washington. The original crystal weighed 45 kg.

Color and iron: Aquamarine gets its color from divalent (Fe²⁺) and trivalent (Fe³⁺) iron. The combination produces blue-green color; heat treatment removes Fe³⁺ leaving only Fe²⁺ — resulting in pure blue. Most light blue aquamarine is heat treated.

Aquamarine vs. blue topaz: Blue topaz (often irradiation-treated) is a common less expensive alternative to aquamarine. Both are blue, but topaz has greater dispersion and a slightly different tone. A gemologist can differentiate with a refractometer.

Cut school: Aquamarine is ideal for large "clean" stones without inclusions — emerald cut (step cut) shows clarity and color in the best light. Oval and cushion cuts are also popular. Brazilians developed special cutting techniques for enormous crystals.

Aquamarine is an accessible colored stone — Brazil (Minas Gerais, Santa Maria de Itabira) is the leading source. Despite accessibility, high-quality "Santa Maria azul" blue and exceptional size (above 10 ct) are premium.

The world's largest faceted aquamarine is the Dom Pedro (13,905 ct) — an obelisk carved by German artist Bernd Munsteiner from a single Brazilian crystal. It is displayed at the Smithsonian in Washington.

Naturally blue aquamarine (without heat treatment) is rarer — most of the commercial supply is blue-green in raw form and is recolored by heating.

Aquamarine is a variety of beryl — the same mineral as emerald. The difference is in color and clarity: emerald contains chromium and is dark and full of inclusions; aquamarine contains iron and is typically exceptionally clean.

Heat treatment of aquamarine is an entirely natural process: when heated to 400–450°C, Fe³⁺ ions are reduced, the yellowish-green component disappears, and pure blue Fe²⁺ remains. The process is reversible with radiation, but in practice untreated stones remain blue-green.

The "Dom Pedro" aquamarine was carved from a crystal that was initially broken with dynamite during excavation. Munsteiner received three pieces — from one he created the Dom Pedro, the world's largest faceted gem (a 53 cm tall obelisk with complex internal facets).

Hydrothermal synthetic aquamarine exists — GIA CS states: "Russian growers produce hydrothermal synthetic aquamarine, but it is not widely available." Synthetic beryl in various colors (including aquamarine) is produced in Russia but rarely reaches the jewelry market.

The most common aquamarine imitations on the market are:
- Heat-treated blue topaz (Sky Blue, Swiss Blue, London Blue) — most common alternative; more accessible price; gemologist distinguishes with refractometer
- Cobalt-colored synthetic blue spinel — GIA: "most convincing imitation of aquamarine"; distinguished with spectroscope (cobalt absorption spectrum)
- Blue glass — crude imitator

For buyers: real aquamarine has double refraction (birefringence) that topaz lacks to the same degree; GIA certificate confirms. Untreated blue-green aquamarine is now specifically promoted by some dealers precisely to differentiate from treated topaz.