Aquamarine, the Optical and Oracular Gemstone

Albertus Magnus

Albertus Magnus

Take the stone which is called Beryllus. It is of pale colour and may be seen through as water. Bear it about with thee, and thou shalt overcome all debate, and shalt drive away thy enemies, and it maketh thy enemy meek. It causeth a man to be well mannered, as Aaron saith. It giveth also good understanding.

Albertus Magnus (c. 1193–1280)

Book of Secrets

In ancient times, emerald (smaragdus) and aquamarine (beryllus) were classified as separate gemstones because of their color. In reality, the range of color in emerald and aquamarine is not always so distinct. In the 1st century, Pliny the Elder described several stones under the rubric of beryllus, but he also astutely observed that some considered smaragdus to be the same or at least very similar to them.


Aquamarine (Left) vs. Emerald (Right)

crystal skull

Rock Crystal Skull

We now know that emerald and aquamarine are both beryllium aluminum silicates, or beryls. The mineral beryl comes in many colors depending on the type and amount of trace elements contained in its crystal structure. An emerald’s intense green is caused by traces of chromium or vanadium. The trace element iron adds a touch of blue to the emerald, and it is the primary coloring agent in aquamarine. There are no established criteria for distinguishing lightly colored emeralds from aquamarine in the gem trade. However, it is generally agreed that aquamarine exhibits lighter tone and saturation than emerald. A very pale aquamarine can also resemble glass, and for this reason, ancient scholars such as al-Biruni considered aquamarine and rock crystal (quartz) to be related.

crystal berylThe Beryll of the ancients comprehended under it, all other jewels which are like unto a Crystall, with somewhat a diluted colour…The Italians do until this day call Crystalls which have some colours in themselves by reason of the reflexion in the angles, Berylls.

Thomas Nicols (1652)
A Lapidary, or The History of Pretious [sic] Stones with Cautions for the Undeceiving of All Those That Deal With Pretious [sic] Stones

Pliny the Elder

Pliny the Elder

In ancient times, a gem’s color determined the type of sickness it was thought capable of curing. Green was regarded as the color most beneficial to the eyes, and as a result, emerald and aquamarine were commonly used for aliments of the eyes. According to Pliny the Elder: “If the sight has been wearied or dimmed by intensively looking on any other subject, it is refreshed and restored by gazing at this stone. And lapidaries who cut and engrave fine gems know this well, for they have no better method of restoring their eyes than by looking at the emerald, its soft, green color comforting and removing their weariness and lassitude.”

Nero aquamarine

Detail of Nero Watching a Spectacle, from a Painting by Henryk Siemiradzki (1876)

Pliny went on to relate that the Roman Emperor Nero (AD 37–68) used an emerald to view gladiatorial competitions. King (1865) opines that the “stone must have been hollowed out at the back and thus have acted as a concave lens in assisting his sight to distinguish clearly what was going on so far below the imperial seat. But this virtue then must have been ascribed to the material, not to the form of the stone.”

modena fresco

1352 Fresco by Tommaso da Modena in the Church of San Nicolò, Treviso

Fortunato Pio Castellani, a famous 19th century jeweler, admired and copied the craftsmanship of ancient jewelers. In his Gems, Notes and Extracts, he indicated that: “It appears that the ancients applied the term ‘beryllus’ also to a magnifying glass, and perhaps they used aquamarina for the same purpose. This supposition is rendered probable from two reasons; the first is that in the German language spectacles are called ‘brille,’ and no other derivation has been found for this word than the Latin ‘beryllus;’ the second is that Nero is said to have looked at the spectacle in the theatres through a very large emerald. We have already seen how easily the ancients confounded the emerald with the beryl, and therefore we do not think it unlikely that Nero’s emerald was an aquamarina cut for the purpose of a magnifying glass. In corroboration of the above, we bring to the notice of the reader the fact that Nicola de Cusa, Bishop of Brixen, who died in 1454, gave the name of Beryllus to one of his works for this reason, that ‘by means of its assistance, people could understand things otherwise incomprehensible’; and in the second chapter he expressly says: ‘the beryl is a bright, transparent, colourless stone, to which a concave or convex form is given by art, and by means of which whoever looks through it sees things otherwise invisible to the naked eye’.”

Raphael magnifying lens

Detail of Raphael’s _Portrait of Pope Leo X_ (c. 1518)

In King’s opinion (1867), “Mediaeval glass being never colourless, but always tinged more or less with green the resemblance as to colour and form of a lens in such a material to an actual Beryl was sufficiently obvious to induce the communication of the name to the new discovery.” And according to Ball (1950), in 16th century England windowpanes were ‘berills’ and mirrors ‘berral-glas.’ In Ball’s opinion, anything made of green-tinted glass was beryl and “this may well explain the statement that beryl globes were used in divination in the Middle Ages.”

The crystal ball

_The Crystal Ball_ by John William Waterhouse (1902)

As Ball indicated, at one time beryl was associated with scrying. According to Fernie (1907), “That particular crystal which has ever found most favour for the purposes of Crystallomancy through the medium of Crystal-gazing is the Beryl…The favourite shade of this Crystal, as used by ancient seers, was that of the pale water-green Beryl, or delicate aquamarine; this water-green being astrologically considered as a colour especially under the influence of the moon, an orb exerting great magnetic influence.”

Kozminsky (1922) described other means by which beryl was used for ‘seeing’: “In the ‘water divination’ of the Middle Ages a beryl stone was suspended just to touch the surface of the water in the bowl, and it answered questions by automatically striking the edges of the vessel. It was also thrown into a shallow dish of water, information being gathered from the reflections seen in sunlight in the water.”

aquamarine optical attribution