There is a story, probably apocryphal, that the Mughal emperor Aurangzeb was presented with an emerald so included with internal fractures that his gemmologist described it as more crack than crystal. Aurangzeb is said to have asked the gemmologist to leave his presence. He bought the stone.
I think about this story every time someone tells me that inclusions are a flaw in an emerald. They are not a flaw. They are the condition of the stone's existence. Emeralds grow in geological environments so chemically hostile that a truly clean emerald (one with no visible internal features at all) is almost certainly synthetic. What you are buying, when you buy a natural emerald, is a stone that has been pushed through roughly forty million years of tectonic stress and hydrothermal activity and has arrived, improbably, still green and still intact. The inclusions are the evidence of that. They have a name: jardin, from the French for garden.
Understanding this is the prerequisite for buying an emerald well.
In Brief: Emerald is the most included of the major precious gemstones, and its inclusions are accepted rather than penalised at any reputable grading level. Colour is the primary value driver: the benchmark is a vivid, medium-toned pure green or slightly bluish-green, associated above all with Colombian stones from the Muzo mine. Oil treatment — infilling surface fractures with cedar oil or resin — is standard practice applied to roughly 99% of commercial stones; what matters is the degree of treatment and its disclosure. For jewellery rather than investment, a well-coloured Zambian stone with minor treatment at a reasonable price is frequently the better decision than a lightly treated Colombian stone at twice the price.
The four things that actually determine value
Colour, first and overwhelmingly. The ideal emerald colour is a vivid, saturated green with a slight blue cast — the shade described by the trade as "pure green" or "bluish-green," associated above all with the Muzo and Chivor mines in Colombia's Boyacá department. The colour should be intense without being so dark it loses its glow in indoor light. A stone that looks magnificent in sunlight and black in a restaurant is not a good emerald. A stone that maintains its saturation across light conditions (still vivid under artificial light, still readable as green in shade) is the quality standard worth chasing.
Colour is so dominant as a value driver that a superbly coloured Zambian stone with more visible inclusions will often be a better purchase than a lightly included Colombian stone with mediocre colour. The certificate's origin line matters less than what you see in the stone.
Clarity, with appropriate expectations. Emeralds are classified by gemmologists as Type III gemstones, meaning inclusions are expected and normal. The relevant question is not whether the stone has inclusions but whether they are visible to the naked eye at normal viewing distance, and whether they compromise the stone's structural integrity.
An emerald with inclusions visible under a loupe but not to the naked eye at arm's length is a fine stone for jewellery. An emerald with a prominent fracture reaching the surface, particularly one that has been heavily filled with oil or resin to disguise this, is a structural risk. Eye-clean stones exist and command premiums, but they are exceptional. For most buyers, visible jardin is not a problem; visible fractures threatening the stone's integrity are.
Treatment, disclosed and graded. Approximately 99% of commercial emeralds have been treated with oil or resin to improve the appearance of surface-reaching fractures. This is industry standard and does not, by itself, disqualify a stone. What matters is the degree of treatment, described by GIA and other laboratories on a scale from None through Insignificant, Minor, Moderate, and Significant.
Minor treatment is acceptable for jewellery purposes. Moderate treatment is borderline. Significant treatment is a meaningful reduction in value and durability, because heavily filled fractures can leak oil over time, particularly when exposed to heat or ultrasonic cleaning. Any reputable seller should be able to tell you the treatment grade of their stones without hesitation. "We don't have that information" is not acceptable for any stone above approximately £500.
Origin, with honest caveats. Colombian emeralds from Muzo command a 30 to 60 percent premium over Zambian stones of equivalent colour and clarity. This premium reflects prestige and historical association rather than objectively superior quality. The finest Zambian stones from the Kagem mine area are often cleaner and equally saturated, and the colour difference (Zambian stones tend slightly bluer-green, Colombian stones slightly warmer) is a matter of preference rather than hierarchy. For buyers who are not purchasing for investment or resale, paying the Colombian premium requires a conscious decision about what you are buying. For investment and resale, Colombian origin with laboratory certification is the more defensible position.
Ethiopian emeralds from the Shakiso region are a newer source, discovered in 2016, that produce vivid stones with strong colour at prices below both Colombian and Zambian equivalents. Worth knowing as an option, though the prestige premium is not yet established.
Where they come from
Colombia is the benchmark. The Muzo, Chivor, and Coscuez mines in the Boyacá department have been producing emeralds for approximately five hundred years, and the finest material (described by the trade as "Muzo green," characterised by a deep, pure green with exceptional saturation) remains the global standard against which all other emeralds are measured. Colombian emeralds form in sedimentary rock through hydrothermal processes, which produces the warm green associated with chromium.
Zambia has emerged over the past two decades as the most serious competitor to Colombia. The Kagem mine, in the northwest of the country, accounts for roughly 25% of global emerald supply. Zambian stones grow in metamorphic rock and contain higher iron content, which produces the slightly cooler, bluish-green tone that differentiates them from Colombian material. Their clarity is often superior, with fewer inclusions than comparable Colombian stones. The price is typically 30 to 50 percent below Colombian equivalents.
Brazil produces large, clean rough at accessible prices. Brazilian stones tend toward a lighter, yellower green than Colombian or Zambian equivalents. Useful for buyers seeking size at reasonable cost, less competitive for colour quality at the top end.
Ethiopia (Shakiso) is the emerging market. Stones discovered there since 2016 can rival Colombian colour in vivid examples and arrive at prices below established origins. Certification is important here because the origin premium is not yet priced in.
Treatments explained
Oil treatment is the primary variable that most buyers do not understand before they buy.
All emeralds form with surface-reaching fractures called fissures. These fissures, when they reach the surface of the cut stone, can be filled with cedar oil or resin with a similar refractive index to the stone, making the fissures less visible and the stone appear clearer. The process is reversible in the case of cedar oil, which can leach out over time, particularly when exposed to heat, ultrasonic cleaning, or steam. Resin-filled fissures are more stable but cannot be re-treated.
The consequence for buyers: a heavily oiled emerald may look significantly better in a shop than it will look after a year of daily wear, as the oil migrates out of the fissures. An emerald with moderate treatment should never be cleaned with an ultrasonic cleaner. A stone with a GIA or GRS report noting "significant" treatment is a stone to approach with care regardless of how it looks in the display case.
The stones worth seeking are those with "none" or "insignificant" treatment at the laboratory grade level. These are rarer, carry a premium, and are the right choice for anyone buying at investment level. For jewellery wear at a reasonable budget, "minor" treatment is standard and acceptable.
What to look for when buying
Colour in multiple light conditions. This is the single most important test. Assess an emerald in daylight, in fluorescent lighting, and in candlelight or warm incandescent if possible. A stone that looks vivid in all three is the quality you are after. A stone that looks wonderful in one and washed-out or muddy in another has a conditional colour that will disappoint over time.
Structural integrity. Look at the stone from multiple angles with the naked eye before any loupe examination. A large fracture running through the body of the stone is visible without magnification. Any crack that reaches the girdle (the edge of the stone) is a fracture that makes the stone vulnerable to chipping on impact. For an engagement ring worn daily, structural integrity is not a minor consideration.
A laboratory report for stones above £2,000. GIA, GRS, Gübelin, and AGL are the recognised authorities. The report gives you colour grade, clarity grade, treatment disclosure, and origin opinion. For stones below this threshold, a jeweller's verbal disclosure of treatment is the minimum. No disclosure at all is a reason to leave.
Certification versus appearance. A mediocre stone with an excellent certificate is still a mediocre stone. Look at the stone. If the colour does not move you in the shop, under good lighting, it will not move you when you get it home.
Quick reference
| Factor | What to prioritise | What to avoid |
|---|---|---|
| Colour | Vivid, medium-toned green; consistent across light conditions | Pale, grey, or strongly yellowish green |
| Clarity | Eye-clean or near-eye-clean; jardin acceptable | Large fractures reaching the girdle; heavy black inclusions through the table |
| Treatment | None, Insignificant, or Minor per laboratory | Significant treatment without disclosure |
| Origin | Colombian for investment; Zambian for value | Unverified origin claims without certificate |
| Certificate | GRS, GIA, Gübelin, or AGL | No disclosure; verbal-only claims |
Where to buy
Leibish & Co carries certified natural emeralds with GRS documentation, including Colombian, Zambian, and Brazilian stones at a range of price points, and provides HD video of individual stones before purchase. One of the few online sources where the certification infrastructure matches the quality of the stones presented.
Vashi is the strongest option for an emerald set in a finished ring in the UK market, with transparent stone specifications and solid quality control at the mid-market price point. Their emerald and diamond three-stone settings are consistently among the better executions available without commissioning bespoke.
The Antique Jewellery Company carries Art Deco and mid-century emerald jewellery where the stones were typically cut from older, deeply coloured rough that is increasingly hard to source from current production. A 1930s emerald in a calibré-cut French platinum setting can offer both quality and design distinction at a price that competes with new stones.
1stDibs offers access to dealer inventory worldwide, including estate emeralds from the Colombian production of the 1960s and 1970s, when significant stones were flowing through the market in large quantities. Condition varies and due diligence is required, but exceptional pieces appear regularly.
For stones above £8,000, Christie's and Sotheby's offer emeralds with full provenance and laboratory certification in their jewellery sales. Pre-sale estimates are published and worth reading as a market reference.
The engagement ring question
A note on emerald engagement rings, since our sapphire guide prompted several questions on this: emerald is not the ideal choice for a ring worn daily. It scores 7.5 to 8 on the Mohs hardness scale, which is adequate, but the natural fissures that characterise most emeralds make it more vulnerable to chipping on impact than a sapphire or diamond. An emerald set in a protective bezel setting, worn with some awareness, is entirely manageable as a daily ring. An emerald in high prong settings, worn through active daily life with no particular care, is a higher risk proposition.
This is not a reason to avoid emerald engagement rings. It is a reason to choose the setting and the stone carefully, and to have the piece checked by a jeweller annually.
Frequently asked questions
Why are emeralds so included?
Emeralds form in geological environments where the crystal-growing conditions are inherently unstable: hydrothermal fluids moving through rock over millions of years under significant pressure and temperature variation. The result is that virtually all natural emeralds form with internal fractures, gas bubbles, and mineral inclusions collectively called jardin. A flawless or near-flawless natural emerald is extraordinarily rare; rare enough that its absence of inclusions is itself a point of suspicion. Emeralds are graded as Type III gemstones by GIA, meaning inclusions are expected and accepted as a normal feature of the stone.
Is Colombian always better than Zambian?
No, and the question is worth examining honestly. Colombian emeralds, particularly from the Muzo mine, produce a warm, vivid green with chromium colouration that is the historical benchmark. They command a 30 to 60 percent price premium over Zambian stones of equivalent quality. Zambian stones, grown in metamorphic rock with higher iron content, produce a slightly cooler, bluer-green and often have superior clarity. For buyers who are not purchasing for resale or investment prestige, a fine Zambian stone at Zambian prices frequently offers better value than a comparable Colombian stone at the Colombian premium. Evaluate the individual stone, not just its origin.
What is oil treatment and does it matter?
Oil treatment fills the surface-reaching fractures in an emerald with cedar oil or resin, making the stone appear clearer. It is applied to roughly 99% of commercial emeralds. The degree of treatment matters: minor treatment is standard and acceptable; significant treatment reduces value and durability, as heavily oiled stones can leach oil over time, particularly when exposed to heat or ultrasonic cleaning. Always ask for the treatment grade before buying. GIA, GRS, and Gübelin laboratories all report treatment on a defined scale from None to Significant.
How much does a good emerald cost?
A fine natural emerald for jewellery (good colour, eye-clean or near-eye-clean, minor treatment) starts around £800 to £1,500 per carat for well-coloured Zambian material. Fine Colombian stones of equivalent colour start around £2,000 to £4,000 per carat. Top-grade Colombian stones with "none" or "insignificant" oil treatment run £5,000 to £15,000 per carat and above. Exceptional material (documented Muzo origin, high colour grade, minimal treatment, above 3 carats) can exceed £30,000 per carat at auction.
What certifications should I look for?
GIA, GRS, Gübelin, and AGL are the four laboratories whose emerald reports are trusted globally. A report from one of these bodies confirms colour grade, clarity grade, treatment disclosure, and provides an origin opinion for stones where this is relevant. For stones above £2,000, a report is worth insisting on. For stones below this threshold, a reputable seller's disclosure of treatment grade is the minimum acceptable due diligence.
Sources: GIA gemstone treatment standards and Type III classification; GRS and Gübelin grading practices for emeralds; current retail pricing from Leibish & Co, Vashi, and Antique Jewellery Company, 2026; Christie's and Sotheby's emerald auction results, 2023–2026; Colombia vs Zambia origin premium data, 2026 market reports.
