written by Diana Jarrett
Who doesn’t love a glorious emerald? Its verdant liveliness bodes of Spring and of new life. But it’s not relegated to one season. We love emeralds all year long. Various natural shades of emerald go from straight (grass) green, slightly bluish green to slightly yellowish green and keep the stone perennially popular with serious gem collectors.
According to GIA, we can thank a certain cocktail of minerals for contributing to their jazzy tint. “Emeralds are formed when chromium, vanadium, and iron are present in the mineral beryl. The varying presence of these three elements gives emerald its range of color. Chromium and vanadium make an intense green color.”
This ancient gemstone is a brightly-hued member of the beryl family. Beryl, you’ll recall, has numerous other colorful members, too. Golden beryl, heliodor, aquamarine, Morganite, goshenite and that unicorn, red beryl (bixbite), all have their devotees.
But emerald’s adoring fan base harkens back to 1500 BC when Egyptians and East Indians stockpiled this dreamy stone. You may be surprised to learn that its popularity then soared on Austrian soil around the 14th century AD. The Egyptian mines were worked on at an industrial level by both Roman and Byzantine Empires, and later by Islamic conquerors. Large-scale mining ceased in Egypt after the discovery of Colombian deposits. Now, only ruins suggest the Egyptian emerald mine’s earlier glory.
Today, Colombia is considered the world’s largest commercial producer of emerald, hauling up between 50–95% of the global production, depending on the year, source and quality of the rough. Zambia comes in 2nd as the world’s biggest producer. Brazil and Australia are engaged in commercial emerald mining as well.
What’s Going on in There?
Irrespective of where the emerald was mined, its crystals are recognized for having specific and abundant inclusions. It’s common for tradespeople to say that one should be wary of any emerald that doesn’t bear these types of internal markers. Called “jardin” (French and Spanish for garden) within the trade, these tell-tale inclusions resemble moss or at least plant-like growths. No two sets of jardin are exactly alike. Therefore, they help serve as an identifier of an individual crystal.
Some suppliers claim that various jardin can also help detect the origin for these crystals too. While it’s not possible to absolutely identify the country of origin solely from its inclusions, there are geological regions which are more likely to produce emerald with certain typical inclusions.
Gem nerds revel at the discovery of multi-inclusions within any mineral specimen. In the case of emerald, it’s actually quite common to locate liquid inclusions filling its cavities. But they might also form with a gas bubble inside the liquid in the cavities, creating a 2-phase inclusion. And as a trifecta in the inclusion department, emeralds are often found to have 3-phase inclusions of gas, liquid, and a crystal formation.
Geology is a major factor in how emerald is mined, because its terrain can be unique to specific regions around the globe. In Colombia for instance, their emeralds are the only ones in the world recovered from sedimentary rock rather than igneous rock. These sedimentary layers are heavily faulted and folded, mostly with shale and argillite and calcite veins. It’s here where miners locate emerald crystals sandwiched in various directions within the shale.
Mining’s a Real Blast
By contrast, emeralds commercially mined in Australia are found mostly in rocks among layers of other minerals like mica. A pit is first dug with shovels, then excavators or earth moving equipment go in, depending on the scale of the area being mined. Emerald-bearing ore that’s beneath substantial rock is treated to an explosive blast to release it out of the ground. Additionally, high-pressure water also blasts the rock exposing its mineral-bearing trove.
All well and good, as many natural fractures and inclusions could have been part of the growth phase of this cheery stone. But one of the more fascinating probabilities is a completely separate reason for its jardin-cracks. The extreme measures of blasting out ore to extract emeralds from their unyielding host results in what the miners refer to as concussive fractures of the material. The harsh mining techniques used to release emerald from its host often create unintended fractures in the crystal rough. It’s that method of mining or nothing, they believe.
With such violent techniques required to harvest the crystals, its small wonder they ever find large sized emerald rough at all. But they do. What is rarer of course, are clean crystals without its iconic fractures and jardin. But those somehow make it into the harvest as well—although rarely. By and large, most emeralds come up from the mines with abundant cracks, fissures, and inclusions. Fortunately, we have a remedy to make them salient.
All Dressed Up and Somewhere to Go
Most emeralds are routinely immersed in oils and resins to reduce the appearance of their inclusions and to improve apparent clarity. After that kind of treatment, they mustn’t be cleaned with ultrasonic cleaners. This will result in the loss of the oil and will likely damage the emerald too. Re-oiling emeralds can be done by professionals though, using specific oil and equipment.
Slender Shape Informs its Cut
Emeralds form in naturally long crystals, which makes a classic emerald cut, or its traditional rectangular shape, an obvious choice for producing maximum yield. But did you know this luxurious gemstone shape is nothing new? Since ancient times, emeralds were known to be brittle and naturally included, making them especially susceptible to fractures. Lapidaries as far back as the early 16th century knew this. So, they developed that rectangular cut, which today is called the emerald cut, as a way to prevent accidental chipping or breakage during the cutting process.
So, fractured or not, we love our greenies. The emerald heralds a burst of freshness, and fortunately for serious colored stone lovers, it flatters many skin tones. Bringing these gemstones to market was a real blast, and aren’t we glad they went through all that trouble?