Emerald Colour: Hues and Quality

From saturated green to deep blue-tinted hues: decoding the shades

Emerald exists in a far wider palette of greens than most people imagine. From the intense, almost blue-tinted green of Zambian stones to the classic Colombian green, each origin carries its own signature. Unlike other precious gemstones where colour remains relatively consistent, emerald shifts in hue depending on where it is mined. The green that has captivated us since Antiquity is not a single shade but a spectrum of distinct nuances, each recognisable to a trained eye.

At Mayuri, we select our Emeralds for their saturated green and clarity, with a preference for Zambian and Brazilian origins. Each stone is individually reviewed by our gemologists before setting. This article decodes the shades of Emerald, the criteria for colour quality, the influence of origin on tone, and the role of treatment in the final appearance.

The reference colour of Emerald is a pure, saturated green, neither too light nor too dark. It is saturation that distinguishes an Emerald from an ordinary green beryl. In gemology, for a beryl to be classified as an Emerald, it must display a sufficiently intense green. A pale green beryl will be described as "green beryl" or "green heliodor," never as an Emerald.

Chromium and vanadium are the chemical elements responsible for this colour. Chromium produces a pure, vivid green with a slight blue tint. Vanadium yields a warmer green, sometimes edging toward yellow. Colombian Emeralds contain primarily chromium, which accounts for their classic saturated green. Zambian stones combine chromium and iron, adding a distinctive blue-tinted quality. Brazilian Emeralds combine chromium, vanadium, and iron in varying proportions, resulting in a broader and more diverse palette.

The gemological definition of Emerald varies slightly between laboratories. The GIA (Gemological Institute of America) accepts Emeralds coloured by vanadium alone, provided the green is sufficiently saturated. The LMHC (French Gemological Laboratory) and the CIBJO (International Confederation of Jewellery) require the presence of chromium. In practice, most Emeralds on the market contain chromium, with or without vanadium.

Colombia produces approximately 70 to 80 percent of the world's Emeralds. The mines of Muzo, Chivor, and Coscuez are the most celebrated. Colombian green is considered the benchmark: pure, saturated, and lightly blue-tinted in certain lights. This green owes its quality to a high concentration of chromium and the absence of iron. The typical inclusions found in Colombian Emeralds are described as "three-phase": a cavity containing a liquid, a gas bubble, and a halite crystal simultaneously. Long considered exclusive to Colombian stones, research published by the GIA in 2014 showed that similar inclusions also exist in emeralds from Zambia and Afghanistan.

The Muzo green is the most sought-after: a true green, neither too light nor too dark, retaining its saturation in all lighting conditions. A top-quality Muzo Emerald can reach $18,000 to $36,000 per carat for stones over 2 carats with no visible treatment.

Zambian Emeralds represent approximately 15 percent of global production. The Kagem and Grizzly mines are the primary sources. The Zambian green is cooler than its Colombian counterpart: blue-tinged, deep, almost ink-like in certain lights. This nuance comes from the presence of iron alongside chromium. Zambian Emeralds are often more transparent than Colombian ones, with fewer inclusions visible to the naked eye.

We favour Zambian Emeralds in our Canopée Emerald collection for their saturated green and exceptional transparency. The price of quality Zambian stones ranges between $6,000 and $14,000 per carat for stones of 1 to 3 carats, approximately 30 to 40 percent less than a comparable Colombian stone. This price difference does not reflect a difference in intrinsic quality, but rather the historical market perception that places a premium on Colombian origin.

Brazil produces Emeralds across several states: Bahia, Goiás, and Minas Gerais. The hues vary considerably from one mine to another. Brazilian Emeralds often contain vanadium, which produces a warmer green, sometimes leaning toward yellow. Certain Emeralds from Bahia display a pale, almost pastel green, placing them closer to green beryl. Others, from Santa Terezinha de Goiás, show a more saturated green, comparable to Zambian stones.

Brazilian Emeralds are generally more accessible than Colombian or Zambian stones, ranging between $2,400 and $9,600 per carat for top-quality stones. Their value-to-quality ratio makes them a compelling choice for contemporary jewellery.

The colour quality of an Emerald is assessed according to three main criteria: saturation, tone, and luminosity.

Saturation measures the intensity of the green. A saturated Emerald displays a pure green, free of grey or brown undertones. Weakly saturated Emeralds tend toward grey or brown and are classified as "green beryl" rather than Emerald. The GIA grades saturation from 1 (grayish/brownish) to 6 (vivid). A superior-quality Emerald displays a saturation grade of 5 or 6.

Tone measures the lightness or darkness of the colour. It is graded from 0 (colourless) to 10 (black). Quality Emeralds fall between 5 and 7.5: neither too light (which would shift them toward green beryl) nor too dark (which would reduce their brilliance). The ideal tone falls around 6 to 6.5: a medium to medium-dark green that retains its vibrancy.

Luminosity measures the stone's ability to reflect light. Unlike a Diamond, where brilliance depends primarily on cut, an Emerald's luminosity depends on its transparency and the absence of opaque inclusions. A heavily included Emerald, even if well cut, will appear dull. Superior-quality Emeralds display sufficient transparency to allow light to pass through without any veil.

The inclusions found in Emeralds are referred to as a "jardin," in reference to their garden-like appearance under magnification. Unlike a Diamond, where inclusions consistently reduce value, the jardin of an Emerald is accepted as long as it does not affect brilliance. An Emerald with no inclusions visible under 10× magnification is exceptional and immediately raises the question of synthetic origin.

Typical inclusions include three-phase inclusions (liquid, gas, and crystal), healed fractures, and crystals of pyrite or calcite. Certain inclusions are sought after by collectors for their identification value: three-phase inclusions often confirm Colombian origin, while tremolite crystals are characteristic of Afghan Emeralds.

Oil treatment is commonly used to conceal fractures. Approximately 99 percent of natural Emeralds on the market have undergone a clarity treatment with cedar oil or resin. This treatment is accepted by all gemology laboratories, provided it is disclosed. An untreated Emerald of superior quality is worth two to three times more than a comparable treated emerald.

We systematically disclose the treatment of our emeralds. All our emeralds are treated with cedar oil, the industry-standard treatment, free from resin or polymer. This process enhances transparency without altering the natural colour.

Our Canopée Emerald collection explores a gradient of natural greens, from dark tsavorite (dark green garnet) to saturated Emerald (intense green beryl) and through to pale tsavorite (light green garnet). This gradient echoes the nuances of a tropical forest, from the shaded undergrowth to the luminous canopy above.

Tsavorite, discovered in 1967 in Kenya by Scottish gemologist Campbell Bridges, is a grossular garnet coloured by chrome and vanadium. It shares with the Emerald the same chemical origin of colour, which explains their visual resemblance. Dark tsavorite displays a deep, almost inky green, comparable to Zambian Emerald. Pale tsavorite reveals a softer, more luminous green, reminiscent of lighter Brazilian emeralds.

This gradient allows several shades of green to be worn within a single composition, playing on contrasts of saturation and luminosity. We offer it across rings, Earrings and necklaces, combining tsavorites and emeralds in 18K yellow, white or rose gold settings.

The Emerald is a dichroic stone: it displays two distinct hues depending on the angle of observation. Viewed perpendicularly to the crystallographic axis, it shows a bluish green. Viewed in parallel, it reveals a yellowish green. This dichroism is more pronounced in chrome-rich emeralds than in those coloured by vanadium.

The cut of an Emerald must take this dichroism into account. The emerald cut (rectangular with cut corners) is designed to maximize saturation by orienting the table perpendicularly to the most saturated axis. A poorly oriented emerald can lose up to 30 percent of its apparent saturation.

Emeralds also shift in color depending on the light source. Under natural daylight (overcast sky, color temperature 6,500 K), an emerald displays its purest green. Under incandescent light (a classic bulb, 2,700 K), it takes on a slight yellow cast. Under cool LED lighting (above 5,000 K), it gains in saturation and depth. Zambian emeralds hold their color better under LED lighting than Colombian ones, which can appear slightly grey under cool artificial light.

The price ranges apply to emeralds of 1 to 3 carats, VS to VVS clarity (Very Slightly Included to Very Very Slightly Included), oil-treated, and accompanied by a gemological certificate. Prices vary considerably depending on saturation, tone, transparency, and the size of the stone.

The colour of emerald is far more than a simple green. It is a geological signature, a story written in chromium and vanadium, a matter of saturation, tone, and luminosity. Each origin has its own nuance: the saturated green of Colombian stones, the blue-tinged depth of Zambian emeralds, the warmth of Brazilian ones. The garden, far from being a flaw, is part of the stone's very identity. Oil treatment, a common and accepted practice, enhances transparency without altering the natural colour.

At Mayuri, we select our emeralds for their saturated green and exceptional clarity. Our Canopée Emerald collection explores a gradient of natural greens, from dark tsavorite to saturated emerald and on to light tsavorite, playing on contrasts of saturation and luminosity. Each stone is individually assessed by our gemologists before setting.