Green Diamonds: Guide for Shapes, Shades, and Rarity in 2021

Green Diamonds
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Green Diamonds: Guide for Shapes, Shades, and Rarity in 2021

Green Diamond: This green diamond has all of the characteristics of a highly desirable colored diamond:

A) It is a natural diamond.
B) The green color was produced by nature.
C) the color is a pure green with rich saturation.

The Gemological Institute of America graded its color as “Fancy Vivid green” with a natural origin and an even distribution.

Facts About Green Diamonds

A natural diamond coming into contact with a radioactive source at some point during its lifetime causes some diamonds to develop a green coloration. The time required may be as much as a million years or longer. Green diamonds of this nature are very unique.

The most common form of irradiation diamonds comes from alpha particles found in uranium compounds or from percolating groundwater.

Green spots on the surface of the diamonds or a thin green film may develop on the skin of the diamond after long exposure to these particles. Many times this green coloration will be removed during the cutting or faceting process.

Bombardment by beta and gamma rays will color the diamond to a greater depth and in some rare case turn the entire stone green.

Heating to temperature to just below 600 degrees Celsius can sometimes also cause a diamond to develop a green ting. Higher temperatures may turn the stone to a less desirable yellow or brown color.

The diamonds crystal’s lattice structure is changed by the bombardment by radioactive particles enough to disturb the equilibrium of the crystal’s structure and produce a green coloration.

Additional heating will distort the lattice further and add or create another color change. Both radiation and heating will permanently distort the diamond structure.

Green Diamonds: Guide for Shapes, Shades, and Rarity in 2021

Some lightly colored diamonds are irradiated to make their color more intense.

This means that low fields of radiation are beamed into the cut and polished stone, darkening the outer part of the stone all the way around. The process is permanent and professionally accepted in the diamond industry.

Probably the largest irradiated diamond is the Deepdene, a 104.88-carat golden yellow cushion-shaped stone. The diamond was sold in Switzerland in 1997 for $715,320.

The highest price ever paid per carat for a colored diamond was $926.315 for a 0.95-carat fancy Purplish Red stone sold at Christie’s Auction House in 1987. A vivid green brilliant at .90 carat was sold for $670,00 per carat in 2000.

The largest natural green diamond in the world is The Dresden Green. It is classified as an “apple-green” color and weighs in at 40.70 carats.

The Gemological Institute of America examined the stone in 1988.

The Dresden Green Diamond was proved to be not only of extraordinary quality but also a rare Type IIa diamond and is considered the largest and finest natural green diamond ever found.

The Dresden Green gets its name from the capital of Saxony where it has been on display for more than 200 years. The earliest known reference to its existence occurs in The Post Boy, a London new-sheet of the 1700s.

Have you seen green diamonds?

Natural-color green diamonds are very rare. Of all diamonds cut into polished gems in any given year, a very small number of them will have a dominant green color.

Diamonds with natural green color are rare enough that many people have never seen one, and those who have seen one are likely to have seen it in a museum exhibit.

You are unlikely to find a natural-color green diamond in a mall jewelry store. But even though green diamonds are extremely rare, there are a few companies who have a long history in the retail colored diamonds business.

So, anyone who wants a natural-color green diamond and can afford one should be able to find a selection of gems to consider.

Natural Green Color in Diamonds

In many green diamonds, the color is confined to a thin layer at the surface of the rough stone. The design and cut of the polished diamond must be carefully planned and executed to conserve as much of that original color as possible.

Even though the faceting might only preserve a band of green color around the girdle and a small amount in the culet, that can be enough to produce an apparent green color throughout the stone. These diamonds often display a green color which is very subtle.

Most green diamonds have a color that is modified by hints of yellow, blue, or gray. Variations in color, tone, and saturation can make a big difference in the selling price of the gem.

The most valuable green diamonds have pure green color, medium tone, and strong saturation. These colored diamonds might earn a color grade of “Fancy Intense” or “Fancy Vivid.” Such gems are exceedingly rare and will fetch premium prices.

What Causes the Color of Green Diamonds?

  1. Formation of Natural-Color Green Diamonds

Diamonds with a natural green color developed that color while they were underground, in rocks that contained small amounts of radioactive material such as uranium or thorium. As the radioactive materials decayed, they emitted radiation that penetrated the nearby diamond crystal.

When this type of radiation enters a diamond, it can knock electrons or carbon atoms out of their position in the crystal lattice. This alteration most strongly influences the outer layer of the diamond crystal.

As a result, the green color is often present as a shallow “skin” on the outside of the diamond crystal. Diamonds with uniform green color throughout the stone are exceptionally rare.

The displacement of electrons and carbon atoms deforms the crystal lattice and changes the way light travels through the diamond.

The deformation causes the diamond crystal to selectively absorb much of the light entering the diamond and selectively transmit wavelengths in the green portion of the spectrum. This green light travels to the eye of the observer and gives the diamond a green appearance.

The green color from natural irradiation is the most common cause of green color in diamonds. However, green color can also be caused by structural defects in the diamond’s crystal structure, caused by the presence of nitrogen, hydrogen, or nickel atoms.

2. Treated Green Diamonds

Ingenious people are always trying improve the color of gemstones to increase their value. They do this by mimicking the processes of nature or applying treatments that alter the color of the gem.

The first documented treatment to produce green diamonds was an experiment done by Antoine-Henri Becquerel, shortly after his discovery of radioactivity in 1896. He irradiated some diamonds to see if they would be altered, and their color changed to green.

In 1904, Sir William Crookes stored a few polished diamonds in radioactive salts. When they were removed from the salt, the diamonds had a green color at the surface and that color extended to a shallow depth.

This method of diamond treatment is not used today because the diamonds can be contaminated with radioactivity that does not decay to safe levels within a reasonable period of time.

The most common laboratory treatment used today to produce a green color in diamonds is the irradiation of polished diamonds with a low-energy electron beam. This treatment has been used since the late 1940s, and it can modify near-colorless or yellow diamonds to produce diamonds with a green color.

Another treatment to produce green diamonds today is to apply a thin coating of silica to the surface of the polished gems. The coating can produce an attractive appearance, but it is very thin and can eventually be worn off by the abrasion of normal wear.

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Diamonds that owe their green color to a treatment should always be sold with a disclosure that the color was produced by treatment, and state the method of treatment.

Because so many buyers prefer diamonds with a natural color, green diamonds colored by treatment generally sell for a significantly lower price than natural green diamonds of similar color, size and quality.

3. Green Synthetic Diamonds

Synthetic diamond crystals have been successfully grown in laboratories in a variety of colors. Synthetic diamonds with a light green color and a greenish-yellow color have been produced when small amounts of nitrogen and boron were incorporated into the diamond.

Green synthetic diamonds have also been produced by irradiating colorless or yellow synthetic diamonds. So, there can be green synthetic diamonds with an “as grown” green color, and green synthetic diamonds that obtained their green color from “post-growth treatments.”

Are Irradiated Diamonds Safe?

Because many green diamonds obtain their color from exposure to radiation in a laboratory (a process known as irradiation), there have been concerns about their safety when used in jewelry.

All companies in the United States that apply radiation treatments to any type of gemstone must be licensed by the Nuclear Regulatory Commission.

These companies must use approved methods to treat the gemstones, then store them in a secure facility until their radioactivity declines below a level that would make them safe for use in jewelry. Only then can they be released for jewelry manufacturing or sale to the public.

The process of gemstone irradiation is very common. Almost all of the blue topaz offered in stores today is colorless topaz that has been irradiated and then heated to produce a blue color. “Swiss blue” and “London blue” are trade names for two of the most common varieties of treated blue topaz seen in today’s market.

Gemstones have been treated by irradiation in the United States for decades with the Nuclear Regulatory Commission actively licensing companies who do the treatments.

Famous Green Diamonds

Two of the most famous and valuable natural-color green diamonds are the “Aurora Green” and the “Dresden Green.”

The Aurora Green

In 2016, a ring containing the Aurora Green, a 5.03-carat, VS2 clarity, Fancy Vivid green diamond, was sold at a Christie’s auction for $16.2 million. That was the highest price ever paid for a green diamond at public auction.

Prior to the auction, gemologists at the Gemological Institute of America graded the Aurora Green and reported that it was the largest Fancy Vivid green diamond with a natural color that they had ever graded as of January 20, 2016.

The Dresden Green

The Dresden Green is a natural green Type IIa diamond with a clarity grade of VS1. It is a faceted gem of 41 carats with a uniform green color.

Some diamond experts believe that it was cut from a rough diamond produced at the Kollur Mine in the Indian State of Andhra Pradesh. Others believe that it was cut from rough mined in Brazil.

The first known record of the Dresden Green is from a 1772 article in a London newspaper. The date of this article corresponds to a time when a number of green diamonds with uniform color were mined in Brazil and brought to Europe.

The Challenge of Cutting Natural-Color Green Diamonds

Most natural-color green diamonds have a color that is only “skin deep.” This prevents many of them from being cut into faceted gems that retain a distinct green color. Diamonds with a green color that is evenly distributed through the stone are exceptionally rare.

When the green color is confined to a thin layer just below the natural surface of the rough, the shape of the finished diamond must be carefully planned to preserve as much green color as possible.

Often the diamond is cut to preserve green color around the girdle of the stone or sometimes to preserve color in the culet. With a small volume of color to start and sometimes only a portion of it remaining, these green diamonds are a special challenge to cut and often have a low color saturation.

Determining the Origin of Green Color

Anyone who contemplates spending significant money on a green diamond should purchase the diamond from a business that has a reputation for selling colored diamonds.

In addition, the diamond and the cause of its color should be evaluated by a trusted laboratory. Two questions are important: 1) is the diamond natural or synthetic; and, 2) is the green color a result of natural processes or treatment by people?

“Origin of color” is an assessment that some diamond grading laboratories include on a diamond identification report for a colored diamond. If you are purchasing a colored diamond, look for “origin of color” on the report.

Some gemological laboratories can reliably determine the cause of color in many green diamonds; however, the origin of green color cannot be confidently determined for every diamond.

It can be difficult to impossible to separate a naturally irradiated green diamond from a laboratory-irradiated green diamond. In cases where the laboratory is unable to confirm the origin of color they will report that the cause of the color is “unknown” or “undetermined.”

When Christie’s sold the Aurora Green, it was submitted for identification and grading to the Gemological Institute of America. The colored diamond grading report prepared by GIA stated the origin and color of the Aurora Green as “natural, Fancy Vivid green, with an even distribution.”

A grading report from a diamond authority such as GIA can support the confidence and comfort of both buyer and seller. The cost to obtain a lab report from a reputable lab is a tiny fraction of the cost of a nice diamond, making it an excellent investment and insurance policy at the same time.

FAQS

Are green diamonds valuable?

The most valuable green diamonds have pure green color, medium tone, and strong saturation. These colored diamonds might earn a color grade of “Fancy Intense” or “Fancy Vivid.” Such gems are exceedingly rare and will fetch premium prices.

What is the price of green diamond?

WeightFancy GreenFancy Vivid Green
0.20ct15,000 per carat200,000 per carat
1.00ct 50,000 per carat500,000 per carat

What makes a green diamond?

Green color in diamonds is caused by exposure to radiation. This natural phenomenon occurs when diamonds come in close contact with radioactive uranium from rocks near the earth’s surface. In rare cases, this radiation can be found in groundwater sources.

How can you tell if a diamond is green?

The Color. Green color diamonds can be found with single, pure color, but most often contain one or even two secondary hues. The various overtone colors of a green diamond found are Yellow, Yellowish, Blue, Bluish, Brown, Brownish, Grey, Grayish, Gray Yellowish, and Grayish Yellowish.

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