March Birthstone: The Mysterious Tale of Aquamarine’s True Blue Color

Two Latin words meaning “sea water” are the origin of the gem name aquamarine. Appropriately, aquamarine’s color is usually interpreted to be greenish blue or bluish green, like the sea. It’s no wonder the name was given to the beryl variety that exhibits that color.

ABOVE: This 33.58-carat cushion-cut aquamarine is a beautiful example of why so many aqua lovers treasure the slightly greenish cast to the gem’s blue. It is the color of the sunlit shallows of a clear sea. Photo Mia Dixon, courtesy Pala International.

Blue-green is the color most commonly associated with aqua, but crystals are found without the greenish component. In fact, they’re found often enough that, through time, they’ve set the bar for the finest color of aqua. The remarkable Midnight Blue Aquamarine sold by designer Graziela, found in a single small source in Brazil, is a case in point.

There are plenty lovers of the blue-green aquamarine color who would disagree that a truer blue is a better blue. But it did mean that, sooner or later, someone was going to try to “improve” the color of greenish stones. Today, many aquas have been heat treated to reduce/remove the greenish tint and feed demand for “the best” aquamarine. The color is stable and doesn’t affect durability, so if you love less-green aqua, you can buy these stones with confidence.

A square emerald-cut, greenish-blue aquamarine of 20.72 carats. Photo by Mia Dixon, courtesy Pala International.

A square emerald-cut, greenish-blue aquamarine of 20.72 carats. Photo by Mia Dixon, courtesy Pala International.

Because a green-less blue aquamarine has been considered the ideal, imitation aquas–like those often seen in inexpensive birthstone rings–are usually created in that “true blue” color. Today those imitations are often cubic zirconia. At one time, they were synthetic spinel.

I bring this up because, many years ago, before heat treatment of aqua became widespread, an acquaintance showed me her new birthstone ring at dinner. The ring was set with an intense, medium-toned stone–the “aquamarine” her husband had “finally” bought her. Why, she asked, are some aquamarine stones so dark?

Her husband, who had been holding forth about something a few seats away, overheard her and suddenly became very quiet.

With good reason: it was obvious the stone was a synthetic blue spinel, not a natural aquamarine. The imitations had a very distinct, very hard-looking intense medium-blue color that looked nothing like a natural colored aqua.

It was clear to me from her husband’s sudden silence that he knew the stone in her ring was a $2 imitation, not a natural aqua that would have cost many times that.

So what to say?

It’s said that a little knowledge can be a dangerous thing. This was a moment when it got me out of a very sticky situation. I decided to bury her question in a blizzard of facts. I told her about chemical composition and how different elements in a gemstone can cause different colors, and that emerald was a beryl, too, and . . . .  At that point, her eyes glazed with that TMI (too much information) look. She smiled and turned to talk to someone else. Her husband started to talk again, convinced that I hadn’t spotted the impostor and his secret was safe from discovery.

Until now.


Sharon Elaine Thompson is a GG and FGA who has been writing about gemstones and jewelry for Lapidary Journal Jewelry Artist since 1987. She also writes a line of birthstone romance novels under the name Liz Hartley.

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