Green Diamond Value, Price, and Jewelry Information

Green Diamond Value

Like any commodity that is both desirable and rare, green diamonds are very costly. In fact, they are one of the top three most valuable diamond colors along with pink/red and blue. The best natural green diamonds have sold at auction for millions of dollars per carat. Even tiny gems weighing a fraction of a carat cost thousands of dollars.

The Impact of Color-Treated Green Diamonds on Value

However, you must understand an important caveat. The same natural radiation that causes colorless diamonds to express a green hue is easy to replicate in a lab, something that we will examine much more closely below. Artificial radiation exposure results in a color expression that is often so similar to the hues of naturally colored diamonds that even professional laboratories can’t tell how the diamond came to be colored. This is a serious issue as there is a huge difference in price-per-carat values between natural green diamonds and treated green diamonds. If you are planning to purchase a significant green diamond, look for gems with an official GIA “origin of color” report that confirms the cause of the hue.

Green Diamond Color Grading System

As is the case for most of the fancy-colored diamond varieties, green diamonds are graded using the GIA’s nine-step “Colored Diamond Color Grading System.” Listed from weakest color expression to most intense, the nine grading levels are: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Dark, Fancy Deep, and Fancy Vivid.

Unlike some of the other green gemstones like emerald or peridot, the hue of green diamonds tends to be soft, neither overly saturated nor dark. They typically achieve a pastel color rather than a particularly deep or rich shade.

Does Green Diamond Make a Good Jewelry Stone?

Gemologists break down the concept of durability into three parts: hardness, toughness, and stability. Hardness refers to a gem's resistance to surface scratching and diamonds are the hardest naturally occurring mineral on Earth. Toughness describes how likely a gem is to chip or break if impacted. Diamonds are moderately tough and their edges, points, and corners are most vulnerable. Green diamonds have the same hardness and toughness scores that colorless diamonds do. Stability, the final category, refers to a gem's reaction to light, heat, or chemical exposure. Here, green diamonds are a little different.

The color of most green diamonds is due to radioactive elements pushing individual carbon atoms out of place. However, the lattice of the diamond crystal can be healed as atoms snap back into place when they are exposed to temperatures of 600°C or higher. As the radiation damage is reversed, the green color is diminished and can vanish entirely. 600°C may sound like an extreme number, but it actually isn't outlandish. A jeweler's torch, for example, can reach this temperature.

Matching Green Diamonds

Matching any fancy colored diamond is a tall task. You need to find stones that share each of the Four Cs (color, cut, clarity, and carat). Since naturally colored green diamonds are so rare, it is extremely difficult to find similar stones. More often, you will see individual green diamonds highlighted in a design.

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If you're not bothered by treated or synthetic diamonds, finding matches is much easier. Synthetic diamonds are grown in batches, and the procedure is exacting and uniform. Thus, creating identical stones is easy.

The History of Green Diamond

The Discovery of the Dresden Green

The first green diamond on record remains the most important in existence — the Dresden Green. The first record of this huge 41-ct diamond dates to 1722, when it was purchased by Friedrich Augustus I. Like most fancy colored diamonds discovered in the eighteenth century, the Dresden green most likely came from the Golconda mines in India. In subsequent years, individual green diamonds have been discovered around the world, but remain a rare and precious discovery.

The Development of Artificially Irradiated Green Diamonds

In 1904, Sir William Crookes discovered he could make colorless diamonds turn green if he buried them in a radioactive compound for a year. His gems were undeniably beautiful, but there was a catch. The newly colored diamonds were very radioactive, and it wasn't safe to wear them. 

The next innovation came several decades after WWII, as progress was quickly being made with respect to nuclear technologies. A circular atomic accelerator called a "cyclotron" was invented. It was discovered that the outermost layer of diamonds could become green without making the gem dangerous to be near. Unfortunately, the green was so shallow that most of it would come off as the diamond was faceted and polished. This sometimes left a feature called an "umbrella" around the culet of the diamonds. You can still find these features in gems set in vintage jewelry. You can still find treated green diamonds in circulation dating from the 1940s.

Modern Irradiation Methods

Currently, there are various methods that are used to create a green hue in diamonds. One technique employs a modern version of the cyclotron called a linear accelerator which is straight instead of round. Diamonds colored by linear accelerators usually show a dual blue/green hue. A second technique involves a nuclear reactor that blasts diamonds with neutrons. These diamonds may also have that blended blue/green color but also pure green that can be pale to dark. 

The advantage of both newer methods is that they make the green hue penetrate deeply within the diamond. This creates an even color expression, something rarely seen in naturally colored diamonds. Additionally, the radioactivity of the gems quickly dips below dangerous levels. Thus, jewelers can set these stones — and consumers can wear them — without much delay. Finally, a diamond colored by natural radiation looks the same as one treated in a lab. As a result, gemologists are automatically suspicious of any green gem that comes in for grading. If they aren't sure of the cause of the color, they will list it as "Undetermined."

Green Diamond Color

It has been reported that about 54% of green diamonds have a blended color featuring a dominant blue hue paired with a secondary yellow hue. After that, about 28% of all green gems have a pure, unmodified color while 12% have a blended blue/green color. It is also possible for green to be mixed with gray or brown.

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What Causes Green Diamond Color?

Now let's take a closer look at the causes of green hue in diamonds.

Green is a complicated color to induce in diamonds and a 2018 Gems & Gemology article by Breeding et al. examines the four separate mechanisms that may accomplish this: absorption by GR1 defects resulting from damage by radiation exposure, H3 defects, absorption initiated by hydrogen impurities, and absorption caused by nickel-related defects. Muddying matters further is the possibility for green diamonds to be colored by more than one of these mechanisms. As most green diamonds are colored by radiation damage (they account for almost half of all green diamonds submitted to the GIA for evaluation and grading), it makes sense to begin our examination here.

Radiation

To understand how radiation affects the diamond crystal and its ultimate color expression, we need to understand what a normal, unaltered diamond crystal looks like. Diamonds are made from carbon atoms that were squeezed so tightly together in the hot interior of our planet that they became locked into a highly ordered and exceedingly stable cubic structure. Thanks to the uniformity of this atomic arrangement, light is allowed to pass through the crystal without interruption which results in a colorless gem. 

There are two primary ways to introduce color expression into a colorless diamond: forcing individual carbon atoms out of place and the addition of chemical impurities in the crystal lattice. Green diamonds may be colored by one or both of these mechanisms.

With regard to the results of radiation damage, Breeding et al. discuss how prolonged exposure to radioactive minerals and fluids is the most common cause of displaced carbon atoms in green diamonds. Basically, individual carbon atoms are forced from their position in the crystal lattice by radioactive isotopes, leaving their slots in the crystal lattice vacant. The dislodged carbon atoms, now formally called "interstitials," then get stuck between nearby carbon atoms still in their usual alignment. The individual affected locations are called GR1 defects. These defects cause the diamond to absorb blue and red hues, resulting in the transmission of green.

Effects of Radiation Intensity and Exposure Time

It is vital to understand that the effect of radiation on a diamond's crystal lattice is directly associated with its intensity and exposure time, as well as the type of radiation that is present. If a diamond is exposed to alpha particles, likely from decaying uranium, at a depth of 24 km or less, only the carbon atoms on the skin of the crystal will be affected. Specifically, the green hue will likely only penetrate about 20µm. This means that the green color is localized only on the outermost layer of the diamond while the inside of the crystal remains defect-free and colorless. Interestingly, it is thought that the majority of GR1 affected green diamonds are exposed to radiation upon arrival at alluvial deposits in the Earth's crust after they have eroded out of their host kimberlite pipes. 

Stronger and longer exposure to either beta particles or gamma radiation will result in carbon atom displacement that penetrates deeper inside the crystal. This can also create strong color zoning inside the diamond. Some of the world's most deeply colored green diamonds sat in highly radioactive conditions for millions of years. The most common radioactive elements that are responsible for creating GR1 defects in diamonds are uranium, thorium, and sometimes potassium.

GR1 Defects

When GR1 defects are created in colorless diamonds, the resulting color expression is often a blended green/blue hue. However, true colorless diamonds are quite rare. More often, diamonds have a least a hint of yellow caused by nitrogen impurities. In fact, about 98% of mined diamonds have some nitrogen incorporated into their crystal lattice. GR1 defects in yellowish diamonds result in a green hue that is usually pure.

GR1 defects by natural causes do not make the diamond itself radioactive and the effects are not necessarily permanent. Rather, they can be healed if the gem is exposed to temperatures above 600°C. This may happen when the diamond is still buried in the Earth or can be generated by a jeweler's torch. Thus, jewelers must be very careful when working with green diamonds not to heat the gem to that temperature and reduce, or even remove, the valuable color.

H3 Defects

The second most common cause of green expression is created by nitrogen impurities paired with a carbon vacancy. When two nitrogen atoms flank a carbon vacancy center, that location is called a H3 defect. H3 defects occur when a diamond that includes both GR1 defects and nitrogen impurities is heated above 600°C. At this temperature and above, individual nitrogen atoms become mobile and migrate toward each other. 

While the process that GR1 defects cause a green expression by absorbing red and blue light is direct and easy to understand, H3 defects work differently. Firstly, they absorb blue light to create a yellow expression. Then, when H3 defects absorb visible light, they simultaneously emit a green fluorescence. If the free nitrogen contribution is low and H3 defects are plentiful, a blended yellow/green body color is created. Unlike GR1 defects which are so sensitive to heat, H3 defects are stable up until a temperature of 2000° C.

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Hydrogen Impurities

The third and fourth causes of green both have to do with chemical impurities that were incorporated into the diamond crystal as it was growing, rather than owing their color to an outside force that altered a mature crystal.

The first of these impurities is hydrogen which causes hydrogen-related defects. Scientists have known that hydrogen impurities can exist in diamonds for decades, yet how they affect the color of their host gem is not well understood due to their rarity. Green diamonds with hydrogen-related defects have complex structures called N3 defects. An N3 defect is defined as three nitrogen atoms surrounding a carbon vacancy center with a single hydrogen atom included in the defect. The color of hydrogen-rich green diamonds often includes a secondary hue of either brown or gray. Currently, scientists do not know the exact stability of green color in hydrogen-rich diamonds when exposed to heat.

Nickel Impurities

Fourthly, a green hue can be created in diamonds that have nickel impurities. These gems are rare, amounting to only about 1% of all green diamonds submitted to the GIA. Nitrogen and hydrogen can become incorporated into the carbon lattice of diamonds relatively easily because of their size - nitrogen atoms are very similar in size to carbon atoms while hydrogen atoms are quite small. It is unusual for nickel atoms to be incorporated into the crystal lattice because it is a significantly larger atomic element. As a result, the individual defect centers can be a complex web of vacancies, interstitials, nitrogen impurities, and nickel impurities all combined. While the precise temperatures that will affect the stability of these diamonds are not known, Breeding et al. state that these gems can likely survive in 2000°C environments, if not higher.

Green Color Anomalies

Scientists have noted that about 5% of green diamonds are not colored by the four mechanisms listed above.

Type IIb Diamonds

One of these exceptionally rare gems are Type IIb diamonds which have boron in their crystal lattice and should be blue, not green. It is thought that if they also have some unmeasurable nitrogen in their lattice which is shielded from detection by the boron, they take on a strong absorption between 400 and 500 nm, reducing blue and allowing green to be transmitted.

Type Ib Diamonds

Another anomaly is green Type Ib diamonds. Type Ib gems have individual nitrogen atoms scattered around their crystal lattice which normally leads to a strongly colored yellow diamond. However, if the gem contains many vacant places where carbon atoms should be (something that happens when a diamond is subject to high levels of heat and pressure which distorts the atomic structure), it will absorb red and express green, often with brown or gray.

Chameleon Diamonds

Lastly, there is a type of green diamond called a chameleon diamond due to its innate ability to change color. If these gems are left in the dark for an extended period (days to weeks) or heated, their green color will change to a yellow or orangy hue. After they are exposed to light or cooled down, the green color returns. See our Chameleon Diamond Buying Guide for more information on this dynamic gem.

Green Diamond Trade Names

Some sellers use trade names to describe their inventory. These are non-standardized terms used to describe the appearance of the diamond. With respect to green diamonds, you may encounter terms like "mint" or "lime." Some dealers will use the term "emerald" which can be misleading. There is nothing technically wrong with this practice, but, because trade names are not held to a universal standard like the GIA's rankings are, it is not a good idea to purchase any fancy-colored diamond based on a trade name description alone. 

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Identifying Green Diamond

Standard Diamond Characteristics

While issues like fluorescence change with the various fancy colors that diamonds can exhibit, some measurements are universal. 

• Using a standard refractometer, diamonds will register as over the limit (OTL). 
• Their dispersion which causes the beautiful multicolored fiery flashes that diamonds are known for is 0.044. 
• They will not show birefringence (also known as doubling) and are not pleochroic. 
• Lastly, their specific gravity (SG) is 3.52 (+/- 0.10).

Absorption Spectrum

As described by Breeding et al. the four causes of green diamonds are characterized by different effects on the visible absorption spectrum which are summarized. This can be overwhelming so let's break it down by coloring mechanism.

GR1 Defect Green Diamond Absorption Spectrum

Diamonds colored by GR1 defects alone show a very broad absorption band spanning from approximately 550-750 nm pulling out longer-wavelength hues. Within this band, look for lines at 594 and 667 nm. You may also observe lines at 496 and 503.5 nm.

H3 Defect Green Diamond Absorption Spectrum

H3 defects have a broad absorption of blue from 420-500 nm and a line at 415 nm if the diamond has nitrogen. This creates a yellow hue. The green fluorescence which is created as a response to visible light makes the gem primarily green.

N3 Defect Green Diamond Absorption Spectrum

There is a lot going on at an atomic level inside green diamonds colored by hydrogen-rich with N3 defects. The nitrogen impurities pull out blue light by creating an absorption band in the shorter wavelengths. Then, two more absorption bands which reach from 620 - 860 nm that have centers at approximately 730 nm and 835 nm pull out longer the wavelengths of light. A line at 615 nm is specifically associated with hydrogen while a line at 478 nm is associated with the nitrogen-rich N3 defects. Additionally, a band at 530 nm pulls out blue light between 500 and 600 nm which produces a gray undertone.

Nickel Impurities Green Diamond Absorption Spectrum

How exactly diamonds with nickel impurities cause diamonds to become green is not entirely understood. It is thought that nitrogen atoms that cause a line at 415 nm, whether they exist on their own or are clustered inside the diamonds, remove the blue. The nickel atoms then create a broad band from 620 - 710 nm that is centered at 690 nm then pulls out the longer wavelengths. This results in a yellow-green body color.

Fluorescence

As noted above, the various green triggers each result in different types of fluorescence. Green gems created by GR1 defects often don't fluoresce at all because the damage caused by radiation dampens the fluorescence response. H3 colored diamonds can show weak to strong green fluorescence. Hydrogen-colored green diamonds often fluoresce yellow while both diamond varieties with hydrogen and nickel may show an uneven blue florescence.

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Clarity Features

You will find that the various coloring mechanisms leave unique characteristics when examining green diamonds under magnification.

When looking at a gem that owes its color to radiation, you are likely going to see radiation stains in the form of more deeply colored green or brown spots on the skin of the diamond. If you are examining a faceted diamond, some of these stains may have been left along the girdle of the gem to add to the overall color expression of the stone and keep the value as high as possible. They may be any shape or size and it is also possible to observe radiation stains present in fractures inside the stone. These stains may penetrate deeper into the gem than the surface green color. Also, the diamond crystal may expand as a result of the radiation leaving stains raised above the surface of the diamond. You may also see internal color zoning patterns.

Since H3 defects involve nitrogen that is interspersed inside the diamond, the whole crystal may show a yellowish green color rather than just the outermost layer. You might see the green color concentrated in parallel bands called "graining patterns". If a strong focused light is shined on the stone, you might see what Breeding et al. call a "watery appearance".

Unlike GR1 defects and H3 defects which have characteristics that may be observed under magnification, green diamonds colored by hydrogen impurities don't have such specific features. That being said, gemologists have noted that diamonds with high concentrations of hydrogen impurities can have internal milky clouds with clearly defined boundaries. If you are especially lucky, you might observe these distinct clouds arranged in a six-rayed star formation.

Diamonds containing nickel impurities don't have any particular features that can be observed with a regular microscope.

Are There Any Synthetic Green Diamonds?

There are two methods used to grow green diamonds in a lab: chemical vapor deposition (CVD) and high pressure/high temperature (HPHT). These diamonds share the chemical, physical, and optical properties of natural diamonds so they make for fantastic, low-cost substitutes.

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Current screening machines in professional laboratories can identify synthetic green diamonds but technology improves with each passing year. Many experts warn that a time when we can't separate natural diamonds from cheaper synthetic ones is approaching.

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Green Diamond Treatments

While laboratories can identify synthetic gems with the proper equipment, determining whether a green diamond's color was created naturally in the Earth or by treatment is much harder. In fact, the GIA is more likely to get an "undetermined" color origin result when analyzing green diamonds than any other fancy colored diamonds. This is because irradiating diamonds to induce a green color via GR1 defects in a lab is cheap and takes only minutes. However, remember that only naturally-colored green diamonds will have radiation stains. Those can't be faked.

Scientists create green hues by irradiating gems using a linear accelerator (linac), nuclear reactor, or exposure to gamma rays. Most frequently, beta particles are used because they penetrate so deeply into the crystal. The resulting characteristics are the same as natural causes and can even stump professional labs. If the color of a gem looks too even and saturated to be natural, chances are it has been treated. Treat such gems with caution and send them to a lab. 

Similarly, H3 defects are also relatively easy for scientists to create in a laboratory setting using irradiation and annealing which is a process of tightly regulated heating and cooling. This has been done with regularity since the 1950s.

Lastly, high pressure/high temperature treatment (HPHT) can turn a brown diamond into a green or yellowish green gem. The HPHT treatment may affect internal characteristics as well as the color. You might see that naturals and fractures may have become frosted or be surrounded with dark graphitization. When looking at the spectrum of an HPHT treated green diamond, you will likely see a broad band between 480 and 500 nm with a line at 415 nm and another at 503 nm. Additional lines at 505 and 515 nm are also possible.

Where are Green Diamonds Found?

Interestingly, while green diamonds are rare, they have been uncovered almost everywhere diamonds are mined. Most green gems unearthed in recent years come from mines in Africa and South America. 

Green diamonds with color caused by natural radiation have been found in alluvial deposits in Brazil, Central African Republic, Guyana, India, and Venezuela.

Interestingly, green diamonds from the relatively new deposit in the Marange region of Zimbabwe include those colored green by radiation caused by GR1 defects and those colored green by hydrogen impurities. The other three types of green diamonds have emerged from many mines worldwide.

Famous Green Diamonds

The Dresden Green

There is one green diamond that stands head and shoulders above the competition, the Dresden Green. This 41 ct. pear-shaped gem, still the largest natural green diamond in existence, was likely unearthed from the Golconda mines in India sometime before 1722. It has a beautiful deep hue with an even color expression, something that is very rare in green diamonds. It is also a very unusual, chemically pure, Type IIa gem that is colored exclusively by exposure to radioactivity.

The Dresden Green is a stone with a great deal of political importance. It was acquired by Friedrich Augustus I, King of Poland and Elector of Saxony in 1726 from a Dutch merchant named Delles. The gem was then named for the capital of Saxony, Dresden. Next, the gem was purchased by Friedrich Augustus II in 1741. Though no official record exists, it is said that the king paid the equivalent of four tons of gold for this stone. Over the years, several settings were commissioned for the Dresden Green by the Saxony rulers to conform to contemporary trends. The gem remains in the possession of the Saxon elector's collection and currently is on display in the Green Vault at Dresden Castle, its home for the past two hundred years. 

The Dresden Green is sometimes called a sister gem to the blue Hope Diamond due to its deep political history and high public profile.

The Gruosi Green

The original rough crystal of the 25 ct. Gruosi Green diamond from South Africa was approximately one hundred carats - a remarkable feat for a green diamond. Cutting so much of the original rough away was a brave choice that ultimately paid off and the resulting gem has a striking and evenly distributed color. Although this gem has never been evaluated by the GIA, it is said to have nearly flawless clarity.

The Aurora Green

The Aurora Green is a beautiful Brazilian rectangular-cut green diamond that weighs 5.03 ct. Graded a Fancy Vivid Green, it sold for more than 3.3 million dollars per carat in 2016. This is the highest recorded price-per-carat value of any green diamond. 

The Ocean Dream

This 5.5 ct. Fancy Vivid Blue Green diamond from the Central African Republic sold at auction in 2014 for 8.7 million dollars. The GIA was able to confirm that the ultra-rare blended color of the Ocean Dream was, indeed, the result of millions of years of exposure to natural radiation.

Green Diamond Sizes

Like many fancy colored diamonds, green gems tend to be quite small. Of the green gems submitted to the GIA, Breeding et al. report that 82% weighed under 2 carats. This is why larger gems weighing more than five carats like the Ocean Dream and Gruosi Green are so special.

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How to Care for Your Green Diamond Jewelry

Like any valuable gem, you want to treat your green diamond jewelry gently. While earrings and necklaces are unlikely to be accidentally impacted, bracelets and rings might get hit so wear them with care. If you have a particularly valuable gem, it is a good idea to set it in a mounting that protects those vulnerable edges and points. You can use the same gemstone cleaning solutions.