the blue gemstone and March birthstone (2024)

What is Aquamarine?

Aquamarine is the name used for gem-quality specimens of the mineral beryl within a color range of greenish blue to blue. The name is used regardless of a stone's tone or saturation. So, aquamarines can range from a very light, almost imperceptible color to stones with a rich vibrant color.

Most aquamarine has a very light color, which can be almost unnoticeable in very small stones. Stones with a rich blue color are the most popular. They are also the rarest and most valuable.

The name aquamarine is derived from a combination of two Latin words: aqua, meaning water, and marina, meaning the sea - the color of the sea. [1]

Table of Contents

What is Aquamarine?
Aquamarine: Birthstone of March

Aquamarine Gemology
Aquamarine Color and Treatment
Maxixe: The Other Blue Beryl
Synthetic Aquamarine
Geological Occurrence
Sources of Aquamarine

Aquamarine: March Birthstone

Many people know aquamarine because it serves as the birthstone for the month of March. Aquamarine rings, earrings, and pendants are popular birthstone gifts.

Aquamarine: Transparent and Translucent

Aquamarine is best known as a highly transparent blue stone. Unlike emerald, the deep green variety of beryl, high-clarity, fracture-free aquamarine is abundant and more affordable. High-clarity, fracture-free stones are also more attractive and less likely to be damaged during wear.

Did you know that nice pieces of translucent aquamarine are also used in jewelry? Translucent aquamarine is often cut into beads and sometimes cut as cabochons. Necklaces strung with beads of pastel blue aquamarine and pastel pink morganite (both color-varieties of the mineral beryl) make a beautiful combination.

We wondered what the gem identification experts at the Gemological Institute of America (GIA) would think of a humble tumbled stone made from translucent blue beryl. So, we packed one up and submitted it to their lab for identification.

We were delighted to see that despite its distinctly translucent clarity and modest cutting style, the GIA lab identified it as follows... Species: natural beryl, Variety: aquamarine. [2] The identity of the stone was based upon mineral species and color. Clarity and shape did not influence its identity.

Aquamarine Gemology

Aquamarine is such a popular gemstone that it can be found in almost any jewelry store in the United States. If you are interested in purchasing an item of aquamarine jewelry, here are a few things to consider:

Durability: Aquamarine has a Mohs hardness of 7.5 to 8, making it one of the harder gemstones. Diamond, ruby, sapphire, topaz, and chrysoberyl are the only popular gemstones that are significantly harder. Hardness is a property that enables a gem to resist scratching. However, aquamarine's tenacity is rated as brittle - which means that the gem can be easily chipped upon impact. A mounting that guards the stone from impact and not wearing the gem during activities that might result in accidental impact are important precautions.

Color: The price of aquamarine is mainly determined by weight and the strength of its color. Gems with a faint blue color are abundant and inexpensive. Gems with a rich blue color are much more expensive because rich color in aquamarine is very rare. A small aquamarine with a rich blue color will cost a lot more than identical-size stones with a faint blue color.

Size: Aquamarine is available in a wide range of sizes. As the size of the gem increases, the strength of its apparent color will also increase. It can be difficult to find a small gem with a rich blue color, but as the size of the stone increases, the opportunity to find strong color also increases.

Aquamarine Color and Treatment

As a member of the beryl mineral family, aquamarine has a chemical composition of Be₃Al₂Si₆O₁₈. Pure beryl is colorless. The greenish blue to blue color of aquamarine is caused by trace amounts of iron.

The iron can occur in two oxidation states. Ferrous iron (Fe²⁺) is responsible for blue color, and ferric iron (Fe³⁺) is responsible for yellow color (which combines with the blue color to produce greenish blue). [3]

Most natural aquamarine has a greenish blue color. Gentle heat treatment can remove the yellow color and transform the gem's color to a more pure and more valuable blue.

Greenish yellow and other colors of beryl can be altered to colors within the aquamarine range by heat treatment. [3] Most of the aquamarine offered for sale in today's market has received heat treatment. The color improvements achieved by heat treatment are thought to be permanent and undetectable by current methods of testing.

Any time a gem has been heated, irradiated, dyed, or undergone other treatments to improve its color, durability or appearance, the seller should disclose that information to the buyer. This information is important to many buyers - even to buyers of low-cost items.

Maxixe: The Other Blue Beryl

Maxixe (pronounced "mashish") is a rare variety of beryl with a dark blue color. The blue color develops while the gem material is still within the Earth by exposure to natural radiation. Unfortunately, the blue color gradually fades to a pale brownish color upon exposure to light. If Maxixe loses its color, it can be irradiated in a laboratory, however, the renewed blue color will also fade.

Maxixe can be separated from aquamarine in the following ways:

1) by its pleochroism (the strongest pleochroic color of maxixe is seen when the maxixe crystal is viewed down its c-axis, but in aquamarine the strongest blue color is seen when viewing the crystal perpendicular to the c-axis),

2) by its response under an ultraviolet lamp (some maxixe will glow a greenish color under both short- and long-wave ultraviolet radiation), and,

3) a lack of iron in its chemical composition (The iron content test will not be reliable for specimens of synthetic aquamarine which have received their blue color from cobalt or another chromophore.)

These tests can also be used to separate synthetic maxixe (also known an maxixe-type beryl) from synthetic aquamarine. [6]

Synthetic Aquamarine

Synthetic aquamarine (lab-grown aquamarine) has been produced by hydrothermal growth methods in Russia since at least the 1980s [4] and since the early 2000s in the Czech Republic [5].

Some synthetic aquamarine receives its color from iron, like natural aquamarine. However, richly colored synthetic aquamarine has been produced using cobalt, copper, and nickel as sources of color. These metals have not been found as sources of color in natural aquamarine. [4]

Much synthetic aquamarine can be separated from natural aquamarine by microscopic examination. However, the growth zoning structures used to identify synthetic aquamarine are more difficult to recognize, especially in light-colored material. Characteristic mineral inclusions and multiphase inclusions can be used to identify natural aquamarine. [6]

It is unusual to see jewelry items disclosed as synthetic aquamarine, lab-grown aquamarine, or other man-made descriptors. These materials may be uncommon in the marketplace or are simply sold without disclosure.

Geological Occurrence

Most gem-quality aquamarine crystals form in cavities below Earth's surface during the late stages of a magma body's crystallization. The cavities provide open space for crystals to grow. The slow underground cooling rate provides the time needed for the development of large crystals. And, the late-stage timing provides the fluids and a supply of the beryllium needed to form beryl, a beryllium mineral.

Aquamarine is usually found in granite pegmatites. Another source is from veins in metamorphic rocks that were mineralized by hydrothermal activity.

If rocks containing aquamarine are exposed by weathering and erosion, the exceptional hardness of aquamarine (7.5 to 8 on the Mohs scale) will cause it to persist in overlying soils and stream sediments. Much aquamarine has been produced from stream sediments. Where it is found in stream sediments suggests that a primary deposit is located upstream.

Sources of Aquamarine

Brazil is the world's leading source of gem-quality aquamarine for over 100 years. It is found there in both pegmatites and alluvial deposits. Afghanistan, Kenya, Madagascar, Malawi, Mozambique, Nigeria, Pakistan, Russia, Tanzania, and Zambia are all sources of aquamarine. India and Sri Lanka have long histories of aquamarine production from alluvial deposits.

Aquamarine has been found at many locations in the United States. To date, almost all of the production has been from small-scale mining, often where multiple minerals are being produced.