Aquamarine is a variety of Beryl which crystalizes prismatically, sometimes vertically striated and occasionally, terminated with small pyramidal faces. The colour ranges from light blue to green. This mineral was first reported in 1747 by J.G. Wallerius and was named for the colour.
The chemical composition is: Be3Al2Si6O18
Hardness 7.5 -8
"The Beryl and Aquamarine are practically the same stone, differing only in colour, the Beryl varying from a bright blue to white, and the Aquamarine, as its name implies, coinciding with Pliny's description of "the gem green as the sea"; like the sea its colour varies from a pale cool green to a deep green. In quite recent years it has become common amongst jewellers and dealers in precious stones to describe all kinds generally as Aquamarines, and therefore it is not unusual to find one merchant describing the green stone as the Beryl, whilst his neighbour gives this name to the blue.
In their compositions these stones are almost exactly the same as the Emerald, and are found in India, Siberia, and Brazil. It has always been revered in the East as the stone of purity, and was considered to be particularly sensitive to personal influence, so that it is frequently given to brides at weddings that the auras of the newly-wedded may blend in the Beryl, preserving and increasing their mutual love. This belief was held by the Romans, and confirmed by Camillus Leonardus who says, 'it renders the bearer cheerful and increases and preserves married love'; also, 'it cures distempers of the throat and jaws, and is good for indispositions of the liver and disorders of the stomach.'
It is appropriately regarded as the Stone of the Seer and Mystic, nearly all of whom will be found to have Scorpio strong in their horoscopes. It is mentioned by Aubrey as particularly favourable for clairvoyants because "it hath a weak tincture of red wherein magicians see visions." This effect, sometimes seen under the influence of changing light, is also noted by Rossetti in his ballad "Rose Mary," where, writing on the powers of the spirits of the Beryl, he describes the stone as—
"Rainbow hued through a misty pall,
Like the middle light of a waterfall."
All varieties of this stone were considered beneficial to married people in keeping the affections true and constant and protecting from slander; and it was also regarded as a sovereign remedy against idleness, a sharpener of the intellect, and as being specially good for mariners and adventurers, preserving them from danger and sickness on sea and land, and efficacious in the discovery of all hidden things."
-The Book of Talismans, Amulets and Zodiacal Gemsby William Thomas and Kate Pavitt 1922