Very Fancy – The Rarest Diamonds Add to Color Your Life
What are Fancy Color Diamonds?
Did you know that diamonds aren’t all colorless? They can come in every color of the rainbow. In fact, the number of hues, tones, and saturations of fancy color diamonds exceeds most of the well-known colored gemstone varieties!
Many people aren’t aware of fancy color diamonds because they are so rare – it is unlikely you’ll come across one in your every-day jewelry store. The conditions in the Earth for a fancy color diamond to form are extremely specific, and extraordinary. This means gemologists and geologists alike get really excited when they see a phenomenal fancy color diamond – because they have a deep appreciation for how unlikely it’s every existence is! Some fancy color diamonds can be 10,000 times rarer than already rare colorless diamonds, so that’s really saying something.
How are Fancy Color Diamonds Graded?
Fancy color diamonds are graded using the 4 Cs, just like their colorless counterparts, however, color is a much more significant factor than any of the other Cs. Fancy color diamonds are cut to maximize the depth and tone of the diamond, versus colorless diamonds, which are cut to maximize light return and hide inclusions.
While the color is the most important when it comes to pricing fancy-colored diamonds, it does not only mean the intensity of color, but any associated modifying secondary colors or tones. Color combinations such as orangy-yellow, or brown-pink are very common. These modifiers also have a large impact on the value of the diamond since diamonds without color modifiers are even more rare. And modifiers that are rarer can increase the value of a diamond as well. For example, orangy-yellow diamonds are more rare than yellow diamonds. So, assessing color of fancy color diamonds is a complex set of evaluating hue (the color), tone (the lightness or darkness), saturation (the intensity), and then balancing that with the secondary modifying colors.
The beauty of modifying colors is that there is literally a fancy color diamond for all tastes. If you like the warmth of a rich brownish pink, or the lemon-lime color of a green-yellow diamond, modifying colors can be a beautiful thing!
Creating Color – Nature’s Miracle
So, what causes the color in fancy color diamonds?
Much like the processes that form natural fancy color diamonds, there are a number of causes of their color. Gemologists must be highly trained in materials science and spectroscopy to have a deep understanding of those causes and determine if a diamond is natural or has been treated or enhanced artificially to cause the color. The reason this is important is there is a huge price difference between natural and treated fancy color diamonds – in the order of hundreds of thousands of dollars PER CARAT!Yellow and Brown
The most common fancy color diamonds are yellow and brown.
Fig. 3: Even one nitrogen atom replacing a carbon atom in concentrations of a few parts per million can cause diamonds to appear yellow. Image @ GSI
Fig. 4: A 20.00 carat natural yellow-brown diamond set in a platinum and 18kt ring designed by Scott West. Image @ LJ West Diamonds
Fig. 5a: An example of the wide range of shades and intensities of brown diamonds and their color modifiers. Image @ Leibish
Fig. 5b: An example of the wide range of shades and intensities of brown diamonds and their color modifiers. Image @ Leibish
Pink and Red Diamonds
Just like brown diamonds, pink and red diamond color is caused by a distortion in the diamond’s crystal lattice, created by the intense heat and pressure from all directions after the diamond’s formation in the earth. The distortions in the crystal lattice absorb green light and transmitting the pink or red color.
Fig. 6: Ten history-making pink diamonds from Christie's auctions. Image @ Christie's
Fig. 7: The 2017 Argyle Pink Diamonds Tender offered a choice of 58 diamonds weighing a total of 49.39 carats. There are an assortment of fancy pink, red, and violet diamonds. Image @ Argyle Diamonds
Fig. 8: The Argyle Everglow, a 2.11-carat Fancy Red diamond, is the largest red diamond in the 33-year history of the Argyle Pink Diamonds Tender. Image @ Argyle Diamonds
Boron is the active “ingredient” in blue and gray diamonds, bonding with carbon to absorb red, yellow and green light. Blue diamonds occur in hues ranging from green-blue to gray-blue. Green and gray are the most common modifying hues. Blue diamonds make up only about 0.1% of the world’s fancy color diamonds.
The most famous blue diamond is the Hope Diamond, a fancy dark grayish blue.
Fig. 9: The Famous Hope Diamond. Image @ Smithsonian Institution
Green Diamonds
Green diamonds are some of the most complex to test and analyze for diamond scientists. This is because their color is primarily caused by irradiation, and it’s nearly impossible to tell the difference between natural and human-induced radiation.
Diamonds with a natural green color are rare enough that many people have never seen one, or if they have, it has been in a museum exhibit.
In the case of Green Diamonds, their origin of color is quite different from other colored stones. It is exposure to radiation during the diamond’s formation that causes the beautiful green color.
It is not until the last leg of their journey to the Earth's surface that diamonds get their green color. While underground, nearby rocks that contained small amounts of radioactive materials such as uranium and thorium decayed, and emitted radiation that penetrated the nearby diamond crystal.
Fig. 10: The wide array of different shades and hues of green diamonds. Image @ Leibish & Co.
This knocks electrons or carbon atoms out of the diamond’s crystal lattice, especially on the outermost layer or “skin” of the diamond. These missing electrons or carbon atoms change the way light interacts with the diamond and so it selectively transmits wavelengths in the green part of the spectrum, making the diamond appear green.
The green color in diamonds can also be caused by impurities such as nitrogen, hydrogen, or nickel.
Because the color of green diamonds is often limited to the outermost surface, diamond cutters are careful to cut the diamond in a way to preserve as much of that layer as possible. This also helps diamond scientists determine that the cause of the green color is from natural Earth processes.
Green diamonds can have a variety of appearances and modifying colors for a dazzling array of shades, tints, and tones. Modifying colors can include yellow, blue, brown, gray, gray-yellowish, and more.
Fig. 11: The Aurora Green was bought in 2016 by Chow Tai Fook Jewellery for US$16.8 million, which was the most ever paid for a green diamond. Image @ Chow Tai Fook
Orange Diamonds
Orange diamonds require a specific combination of factors to cause their color. They most often have a single nitrogen component to their color but also require a component of plastic deformation. This makes sense as orange is a combination of yellow (caused by nitrogen) and pink/red (caused by plastic deformation). Another lesser understood cause of orange diamonds called the “480 nm band” because of where the orange diamond absorbs light. It is associated with pairs of nitrogen atoms along with single nitrogen atoms, or perhaps substitute oxygen atoms in the diamond lattice.
Orange diamonds with no modifying hues are especially difficult to come across because by their nature, they are a combination of different causes of color. Yellow, brown, or pink are the most common secondary hues found in natural fancy orange diamonds. Pure orange diamonds are almost as rare as fancy red diamonds!
Fig. 12: In 2002 actress Halle Berry was lucky enough to wear the Pumpkin diamond set in a ring to the 74th Academy Awards. She wore it on her little finger while giving her speech as the first African American to win an Oscar for Best Actress.
Purple and Violet Diamonds
Fig. 13: The Argyle Violet from LJ West Diamonds.
Purple colored diamonds are also the product of lattice distortion, but the presence of hydrogen or boron also contributes to their hue. Many of the world's violet diamonds originate from the Argyle Mine in Kimberley, Western Australia.
Pure violet diamonds with no secondary hue almost never occur in nature, and when it does, these diamonds only occur in small sizes. The violet-colored diamonds found in nature usually appear with gray or blue as a secondary hue.
Violet diamonds with their color caused by boron are bluer, with increased gray, and those with the color caused by hydrogen are more violet in color.
Gray Diamonds
Gray diamonds come in a variety of shades, from dark and dramatic to light and silvery. They can be found with a speckled appearance (called salt-and-pepper diamonds) due to inclusions.
Gray diamonds are caused by hydrogen, boron, or dark inclusions.
White Diamonds
White diamonds are often thought to be transparent colorless diamonds that are often incorrectly referred to as “white”. White diamonds are actually diamonds that are a milky white, caused by nanometer to micrometer sized inclusions that scatter or absorb light to cause a whitish color.
White diamonds are different than diamonds that are on the D-Z scale.
Black Diamonds
There are several different causes of color for natural black diamonds: dark inclusions (such as graphite, carbon, sulphides, or clouds), radiation on the surface or in internal fractures, or the defects that can cause green or violet diamonds that are so dark they appear black.
Fig. 14: The Black Orlov diamond is a rare, natural black diamond is 67.49 carats, and its color uniquely described as “gun-metal”.
Treated Natural and Laboratory-Grown Fancy Color Diamonds
It is important to note that most natural diamonds can be treated using irradiation, annealing (heat), and combinations of pressure and temperatures, or even surface coatings to turn diamonds different colors. These treatments must be disclosed.
Also, laboratory-grown diamonds can be grown, or post-growth treated to be almost any color as well. Most common laboratory-grown fancy color diamonds are yellow, blue, and pink. Yellow laboratory-grown diamonds are usually grown by doping the growth process with nitrogen. Blue diamonds are grown by doping the growth process with boron. Pink diamonds are usually treated post-growth with a combination of irradiation and annealing to obtain a pink color, which is totally different than the cause of color in most natural pink diamonds.
Conclusion
As you can see, diamonds come in every color of the rainbow. They span a range of hues, tones, and saturations. They also span a range of rarities, types of formation, and causes of color. They can be cut in any shape or size. There really is a fancy color diamond for everyone!
To ensure the color of your diamond, request that your diamond is accompanied by a GSI report. Each diamond is independently verified as natural and graded to the highest standards and level of integrity by GSI’s leading team of expert diamond graders.