Introduction

The word “emerald” comes from smaragdos, ancient Greek for a green gem. Roman author Pliny the Elder, who died in the 79 CE eruption of Mt. Vesuvius, wrote in his encyclopedic Natural History that “nothing greens greener.” He also stated that the May birthstone had therapeutic properties that helped gem cutters: “(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.” Science now proves this belief: The color green relieves stress and eye strain.The green birthstone was also thought to have magical powers. By placing it under the tongue, one could see into the future. Some believed it made one an eloquent speaker and exposed lovers who made false promises. Emeralds belong to the mineral family known as beryl: several different varieties of the mineral exist including aquamarine, morganite and heliodor, but the green emerald is the most prized and valuable. A rare combination of uncommon geological and geochemical conditions are required for the formation of emeralds.

The Crown of the Andes boasts an impressive 24 ct emerald center stone and 442 additional emeralds set in the intricately crafted golden headpiece. Photo: the Metropolitan Museum of Art/ GIA

According to the classical model, Beryllium, essential for crystallization of Beryl, is one of the rarest elements in the Earth’s crust (estimated to be about 2 parts per million), and must be carried up to the surface by pegmatites, which in turn must come in contact with Chromium & Vanadium bearing (ultramafic) rocks to attain the desired colour.
Notably, not all pegmatites are Beryllium bearing and even fewer are emplaced within country rocks with adequate Chromium. This, coupled with even more specific temperature, pressure and fluid content requirements, makes emeralds extremely rare and remarkably erratic in its distribution.Emeralds vary in colour depending on their chromium, vanadium and iron content. In colour they range from bright green with yellowish undertones, to vibrant green with bluish undertones. Emerald is a cyclosilicate and its composition is (Be3Al2(SiO3)6).

An emerald cross and gold rosary recovered from the Nuestra Señora de Atocha shipwreck. Courtesy: Eileen Weatherbee. Photo: Robert Weldon/ GIA

Color

In gemology, color is divided into three components: hue, saturation, and tone. Emeralds occur in hues ranging from yellow-green to blue-green, with the primary hue necessarily being green. Yellow and blue are the normal secondary hues found in emeralds. Only gems that are medium to dark in tone are considered emeralds; light-toned gems are known instead by the species name green beryl. The finest emeralds are approximately 75% tone on a scale where 0% tone is colorless and 100% is opaque black. In addition, a fine emerald will be saturated and have a hue that is bright (vivid). Gray is the normal saturation modifier or mask found in emeralds; a grayish-green hue is a dull-green hue.

A stunning 24 carats emerald with pure green color from one of our Rough Lots

Cut


Emerald is a relatively hard gemstone – about 7.5 or 8 on the industry-standard Mohs scale, where talc is 1 and diamond is 10. Yet it is also brittle, and this, together with the presence of jardins, can make it a challenging gemstone to cut. The so-called emerald cut – rectangular or square, with bevelled edges – was specially developed to show emeralds off to best advantage while minimising the risk of fracturing or chipping. However, emeralds are also available in cushion, oval and pear cuts. Recently the smooth, dome-shaped cabochon cut has become popular, as have non-traditional slices and rough cuts.If an emerald is well cut, it will mask colour variation, inclusions and other imperfections, and not create “extinctions” (dark patches). Badly cut gemstones tend to maximise weight at the expense of brilliance.The gemstone should be well proportioned and symmetrical, with no distortions. It should have sharp facet edges and flat faces – reflections should enter the eye at once, not “roll” across the face – and the gemstone should be free of chips and scratches. When polished well the gemstone should also possess good lustre – in the case of emerald, the desired quality is known as “vitreous”.With emeralds, beware of vulnerable-looking corners. Because emerald is relatively brittle, it is preferable, from a practical point of view, to choose an emerald cut over other traditional cuts, since it reduces the likelihood of damage to the gemstone.

Panjshir Cut Emeralds from our Collection

Emerald Mines

Emeralds in antiquity were mined in Egypt at locations on Mount Smaragdus since 1500 BCE, and India, and Austria since at least the 14th century CE. The Egyptian mines were exploited on an industrial scale by the Roman and Byzantine Empires, and later by Islamic conquerors.

Emeralds are found all over the world in countries such as Afghanistan, Australia, Austria, Brazil, Bulgaria, Cambodia, Canada, China, Egypt, Ethiopia, France, Germany, India, Italy, Kazakhstan, Madagascar, Mozambique, Namibia, Nigeria, Norway, Pakistan, Russia, Somalia, South Africa, Spain, Switzerland, Tanzania, the United States, Zambia, and Zimbabwe

In the US, emeralds have been found in Connecticut, Montana, Nevada, North Carolina, and South Carolina.

In Canada, in 1997 emeralds were discovered in the Yukon.

In Afghanistan, although Emeralds have been reported from Panjshir for literally thousands of years, it has produced commercial amount of emerald only in last five decades.

Sia Kholo Mines, Panjshir, Afghanistan