On the nature of aquamarine
Aquamarine is the blue sister of that famous green gemstone... emerald. Both belong to the mineral family of beryl. When iron is introduced into beryl, which is colorless in its pure state, the result resembles colors reminiscent of the ocean, serene blue to captivating blue-green.
Aquamarine grows in fascinating six-sided prismatic crystals and, like many other types of beryls, can become quite large. Once in a blue moon, an aquamarine over twelve inches long is found! Many of these larger specimens are not only used for gems but also carvings.
On finding aquamarine and what to look for
Aquamarine deposits are scattered all over the world. One place to find this sky-blue colored gemstone is in Pakistan. High up in the Karakoram Mountains there are aquamarine mines, which are often cut into the sides of cliffs.
Other important producers of aquamarine include Brazil and Nigeria. Brazil's Navigator mine was famous for its trove of tourmaline as well as aquamarine. And African sources in general have become more prolific in recent years with Zambia, Mozambique, and Madagascar furnishing the markets with this tranquil blue gemstone.
Not too long ago, aquamarine was also discovered in Vietnam.
In the United States, aquamarines can be found in Colorado, in Wyoming, and in Idaho, however the minerals are in areas that prevent any notable mining endeavors.
In the typical retail market market, aquamarine competes with treated blue topaz for attention from those looking for a lighter blue stone. Aquamarine is less abundant and sells for quite a bit more than equivalent-quality treated blue topaz.
Color. While many other precious gemstones have a wide range of color, aquamarine only spans the blue to greenish-blue section of the color wheel. A deep cerulean blue is considered the most treasured of aquamarine colors -- with perhaps an ever-so-slight greenish tint and a vivid intensity. Usually the purer and more intense the blue color, the more valuable the stone.
However, most aquamarine is a very light greenish blue, which is a very pretty color, but can be challenging. Aquamarines cut for jewelry many times must be large, like over five carats, to exhibit a desirable and lively color. Small gems are rarely saturated enough to be attractive. Some African mines do uncover smaller stones with good color but as far as the market is concerned these smaller, brighter stones are more uncommon and can sell for more per carat than larger stones of the same color.
Clarity. Clarity is not the issue with aquamarines that it is with its sister, the emerald. Most cut aquamarines that you will encounter on the market are clean and free from visible inclusions. In some beryl, and a few aquamarine, crystals, there are enough parallel inclusions -- usually long hollow or liquid-filled tubes -- that lapidaries are able to bring out a hidden cat’s-eye.
Cut. Aquamarines are cut and carved into a bewildering array of shapes, but most commonly seen are emerald cuts and round or oval brilliant cuts. As we've "hinted" before, aquamarine is not only used for jewelry, gem sculptors also use aquamarine for ornamental objects.
Carat. Aquamarine is one of those crystals that are found in very tiny sizes to quite large sizes. Aquamarines have been unearthed that were 100 pounds! While large stones are readily available, it’s difficult to use them for human jewelry. (Now a headdress for an elephant is another story...) So the price per carat tends to decrease for stones above 25 carats.
Historical notes and other interesting facts about aquamarine
Bon voyage. Aquamarine’s name comes from the Latin word for seawater. This semi-precious stone was said to calm waves and ensure sailors' safety at sea.
The color of a happy marriage. Aquamarine was also thought to enhance the happiness of marriages.
A big blue crystal. Many very large aquamarine crystals have been found but the largest so far is from Brazil. It was found in 1910 and weighed 244 pounds. This lovely specimen measured 19 inches long and 15 inches in diameter.
A trick of the eye. Using a dichroscope, you can see aquamarine is almost colorless in one direction and stronger blue in another directions. It's common crystal magic!
Beryl heredity. It has been said that the mineral beryl (the mineral family aquamarine belongs to) protects its wearer against enemies in battle -- or litigation. Those adorned in beryl stones were thought to be unconquerable and known to be amiable, as well as blessed with a quick intellect.
The Dom Pedro. This is the name of the largest faceted aquamarine, which weighs 10,363 carats and measures 14 inches tall and 4 inches wide at the base.
Resources and further reading
The Gemological Institute of America's Gem Encyclopedia.
Gemstones of the World. By Walter Schuman. Our go to book at Grimballs.
Jewels: A Secret History. By Victoria Finlay. An non-fiction adventure through time and place exploring the history of gems.
Smithsonian Institution National Museum of Natural History's Gem Gallery.