Emerald is the most prized and well-known stone of the beryl mineral family, (aquamarine being another). The use of emeralds in jewellery and objects of personal adornment date back millennia; the oldest emerald, from South Africa, is 2.97 billion years old. Emerald is the birthstone of May and the gem of the 20th and 35th wedding anniversaries.

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HISTORY

The lush green hues of emeralds have soothed souls and excited imaginations since antiquity. Its name comes from the ancient Greek word “smaragdus” meaning “green”; Pliny the Elder described emerald in his Natural History book published in the 1st Century AD, and “…nothing greens greener” was his verdict. He described the use of emerald by early lapidaries, who “have no better method of restoring their eyes than by looking at the emerald, its soft, green colour comforting and removing their weariness and lassitude”. Even today, the colour green is known to relieve stress and eye strain.

There are other green gems, for example tourmaline and peridot, but emerald is most often associated with the lushest landscapes and the richest greens. Ireland is the Emerald Isle, Seattle in the US state of Washington, is the Emerald city, Thailand’s most sacred religious icon is called the Emerald Buddha (even though it is carved from jadeite).

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COLOUR

Emeralds occur in a wide range of green colours. The ideal, as described by the Gemmological Institute of America, is ‘vivid slightly bluish green”, although it is not uncommon to see pure green (the rarest) or slightly yellowish green specimens.

Experts still differ on the degree of green that makes one stone an emerald and another stone a less-prized green beryl. If the stone is on the lighter side of what is classified as ‘medium’, most gemmologists, laboratories and dealers do not consider the stone an emerald.

Scientifically, it is the colouring agents that define the variety. Some gemmology laboratories recognize any green beryl coloured by chromium and/or vanadium as emerald, regardless of the tone. Almost all emeralds contain iron as a trace element, though the amount may differ from one mineral formation to another. A beryl variety that owes its green colour to iron only is classified as green beryl.

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MINING

The earliest documented source of emeralds is the Cleopatra Mine in Egypt, dated from around 330 BC – Cleopatra was renowned for her passion for the stone – but the most famous source of emeralds is Colombia. Spanish explorers changed the course of emerald mining with their arrival in the new world in the 16th Century. The Incas had already been using emeralds in their jewellery and religious ceremonies for 500 years. The Spanish, who treasured gold and silver far more than gems, traded emeralds for precious metals. These trades opened the eyes of European and Asian Royalty to the green stones, and Colombia quickly became recognized as the major emerald source of the world; and has dominated the emerald market ever since.

Today, gem grade emerald deposits exist in several locations around the world. These include Brazil, Zambia, Mozambique, Nigeria, Zimbabwe, Tanzania, China, Afghanistan, India, Pakistan, Russia, Australia, the USA (North Carolina) and Ethiopia.

Zambian emeralds are second only to Colombian stones in today’s market, desired for their high clarity, though they can sometimes be darker in colour (most apparent in larger sizes), which does affect their value.

Brazil also produces a large volume of emeralds, although most of it is limited to the commercial grades, with most of the production being for small stones that are cut in calibrated sizes. Of course, every mine can produce extra fine goods as well as low commercial and non-gem material.

UNDERNEATH THE SURFACE

The formation of emerald requires unusual geological conditions, which also makes emeralds brittle in comparison to other gemstones. Due to its formation and the mining techniques used, emerald tends to contain fissures and fractures, which can decrease transparency. Looking inside an emerald opens a whole new world; the inclusions can be just beautiful! They are called “jardins” meaning “gardens” in French, so called for their mossy or grassy appearance. A flawless emerald is nearly impossible to find. It is these inclusions that give the emeralds their charm, and the complete lack of them could be an indication of a fraudulent stone. When selecting an emerald, the inclusions to be wary of are ones that reach the surface of the gemstone, as these may lead to cracking. For this reason, most emeralds are treated with oils, usually cedar, to improve their clarity and protect the stone.

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TAKING CARE OF YOUR EMERALD JEWELLERY

Though they are a hard stone, emeralds are sensitive to pressure and household chemicals, and care should be taken when handling them. If you wish to clean your jewellery, use a warm soapy water and a tissue or a soft cloth. Be sure to rinse the stones well to remove soapy residue. Avoid ultrasonic cleaners and steamers when cleaning your emeralds, as they can remove the protective oils that are used to enhance the clarity. Jewellers can also clean pieces for you. Always remove any emerald jewellery before exercising, cleaning, or playing sports.

Emeralds may scratch other gems, and they may also be scratched by harder gems. We recommend to store emeralds away from other gemstone jewellery.

Maria Walker, Jewels Specialist

November 2020