Orange Diamond Value, Price, and Jewelry Information
Quite a few diamonds on the market display orange as part of a multi-hued color. However, orange diamonds with an unmodified hue are one of nature’s rarest gifts. There are so few purely orange gems that mystery surrounding their color expression remains to this day. Interestingly, they are closely related to yellow diamonds which are among the most common of all the fancy-colored diamond varieties. It is only a slight change in the chemical makeup and atomic orientation in diamonds that causes them to be orange, rather than yellow. Let’s explore this lively gem which can sell for millions of dollars per carat.
13 Minute Read
Quite a few diamonds on the market display orange as part of a multi-hued color. However, orange diamonds with an unmodified hue are one of nature’s rarest gifts. There are so few purely orange gems that mystery surrounding their color expression remains to this day. Interestingly, they are closely related to yellow diamonds which are among the most common of all the fancy colored diamond varieties. It is only a slight change in the chemical makeup and atomic orientation in diamonds that causes them to be orange, rather than yellow. Let’s explore this lively gem which can sell for millions of dollars per carat.
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Orange Diamond Value
The per-carat value of diamonds with an orange color is quite broad. Unmodified orange gems without secondary color are both very rare and very valuable. The few significant gems that have come to auction sometimes sell for millions of dollars. However, most diamonds that express an orange color do so with a secondary color modifier of pink, brown, or yellow. While these are still valuable gems, you don’t see those astronomical prices that the purely colored diamonds are known for.
Because orange diamonds are so rare, their color is by far the most important value factor. This is also true of many of the fancy-colored diamonds. The GIA developed a nine-step grading scale called the Colored Diamond Color Grading System which provides a standardized system to fairly and consistently evaluate color based on the unique combination of hue, tone, and saturation that gems embody. From the weakest to most powerful color expression, the nine grades are: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Dark, Fancy Deep, and Fancy Vivid. Most orange gems that are highly saturated also show darker tones.
Does Orange Diamond Make a Good Jewelry Stone?
Diamonds are known as the hardest mineral on Earth. Fortunately, the color of a diamond usually doesn't affect its durability and orange diamonds are just as strong as colorless gems. Gemologists divide the concept of "durability" into three subcategories: hardness, toughness, and stability. We know that diamonds are supremely hard and they are also quite stable, meaning that exposure to ordinary chemicals like scented soaps and chlorine doesn't hurt them. However, diamonds are not a particularly tough gem. This means that they can chip if impacted with enough force. The most vulnerable places on a diamond are its edges and points.
Matching Orange Diamonds
Matching anything requires that you have enough material to pick through to find similar items. Pure orange gems of natural origin are so rare that finding sets is extremely unusual. It is easier to match up orange gems that have a secondary color and those that have been treated.
Synthetics are also changing the game. As it has become so easy and affordable to grow orange gems, producers can grow identical diamonds.
The History of Orange Diamond
Orange diamonds were originally uncovered a few hundred years ago and the first high-profile mention of them appears in the 1882 book The Great Diamonds of the World: Their History and Romance by gemologist Edwin Streeter. He is credited with being the first to refer to orange diamonds as "fire diamonds," a trade name some still use today.
Orange Diamond Color
Pure orange diamonds are very rare, so you won't find many with a casual online search. More often, diamonds will exhibit a secondary hue of pink, yellow, or brown. It is also not unusual for diamonds predominantly colored by these three other hues to express orange as a modifier. When the contribution of orange is less than 25%, you may see gems described as "orangy."
What Causes Orange Diamond Color?
According to the most recent research, there are a number of ways that an orange color is created in diamonds. Specifically, an orange color expression is thought to come from one of four different defects, or unique combinations of defects, within the crystal structure of a diamond: the 480 nm visible absorption band, isolated nitrogen defects (C-centers) with plastic deformation, H3 defects with plastic deformation, and nitrogen-vacancy centers (NV).
Unmodified orange gems are overwhelmingly colored by the 480 nm band (86%), while the next most important defect is "C-centers" (13%). The H3 defects and NV defects are rarer causes of orange coloration. Additionally, the concentration of nitrogen and the associated defects must be high enough to trigger a noticeable orange color expression. To understand what each of these defects is, we must first grasp what the ideal, unpolluted diamond crystal looks like.
Diamond Crystal Structure
Diamonds are made of carbon atoms that have been squeezed so tightly inside the mantle of the Earth that they become locked in place with each other. When carbon atoms bind together in this way, they do so in what is called a "cubic" alignment. This is a very regular, extremely powerful atomic organization, which explains why diamonds are the hardest substance on Earth. However, perfection is not something that Mother Nature does very often. Rather, the carbon structure of diamonds usually includes chemical impurities, the most common of which is nitrogen.
Gemologists classify diamonds according to the presence of chemical impurities. Type I diamonds contain at least some nitrogen. Type II diamonds are rare and do not have measurable levels of nitrogen. Unmodified orange diamonds are Type I gems.
We can further break down Type I diamonds based on how the nitrogen atoms are incorporated into the crystal lattice by looking at the individual nitrogen centers they include. Type Ia gems contain aggregated nitrogen centers. Approximately 98% of all mined diamonds are Type Ia. If a nitrogen center within the lattice contains two nitrogen atoms that are paired up, that is referred to as Type IaA or an A-center. If the center has four nitrogen atoms that surround a vacancy where a carbon atom should be, that center is called a Type IaB, also called a B-center. Typically, diamonds will have both A and B centers. Individual gems will be categorized as Type IaA or Type IaB depending on which center type dominates.
There is a third option - individual nitrogen atoms may be isolated in the lattice having taken the place where a carbon atom should be located - what scientists call, a substitution. These isolated nitrogen atoms are called C-centers. Because nitrogen atoms are a different size than carbon atoms, the localized area around a substitution is slightly weakened. These gems are classified as Type Ib and most dominant orange diamonds fall into this group.
Why are Pure Orange Diamonds so Rare?
It is thought that all Type I diamonds begin their lives as Type Ib. As mature diamonds sit inside the Earth waiting for the volcanic activity that will bring them to the surface, the prolonged exposure to heat and pressure allows the embedded nitrogen atoms to seek each other out. First, the atoms pair up to create A-centers. Then, if the heat and pressure is maintained, the nitrogen pairs merge to create B-centers.
This is why Type Ib pure orange diamonds are so rare. Isolated nitrogen atoms need to be incorporated into the crystal lattice of the diamond but must not have been allowed to migrate towards each other. More often, gems will sit too long under intense environmental conditions and nitrogen atoms team up, causing the color expression to move away from orange.
480 nm Absorption Band
Now that we have an understanding of the diamond crystal and its nitrogen impurities, let's examine the four potential causes of orange color further.
A recent study showed that approximately 86% of the unmodified orange diamonds examined were colored by a broad absorption band centered at 480 nm which extends to 600 nm. This band absorbs the shorter, blue wavelengths and allows the longer wavelengths to shine through. The 480 nm band is the second most common cause for gems with orange components whose color is not pure. While the 480 nm band is the most common cause of unmodified orange gems, it is actually the least understood of the four causes. Some have speculated that the presence of oxygen during the formation process may contribute to the effect, but this remains hypothetical.
It has been observed that the presence of the 480 nm band occurs in stones where nitrogen atoms are paired up (A-centers) with some rare C-centers present. Thus, orange gems colored by the 480 nm band are usually Type Ia. Often the color expression of 480 nm-colored orange diamonds is subtly patchy. The color may appear uniform, but, under magnification, you may see regions that are yellow or colorless.
Isolated Nitrogen Defects with Plastic Deformation
Secondly, Type Ib diamonds with C-centers that are paired with plastic deformation are the primary defect combination that causes diamonds to have an orange component mixed with other hues. Plastic deformation describes a kind of atomic slippage that occurs when mature diamonds are exposed to high levels of heat and pressure while still inside the Earth's mantle. Plastic deformation also is the cause of both pink and brown hues which is why they often are combined with orange.
It is worth taking a moment to describe plastic deformation further. As mentioned above, the presence of nitrogen atoms slightly weakens the surrounding crystal lattice. It is where these nitrogen atoms exist that a diamond's atoms slide out of place creating what scientists call "deformation lamellae" which are flat planes inside the gem. These thin lamellae, also called "graining", can be as little as 0.1 mm thick and contain color. Nitrogen does not need to be present for deformation lamellae to form as a result of plastic deformation, but, when it is there, that is usually where the graining forms.
H3 Defects with Plastic Deformation
The third atomic confirmation that can lead to orange expression is the presence of H3 centers paired with plastic deformation. H3 centers are individual defects where two nitrogen atoms sit in the crystal lattice with a single carbon vacancy separating them with the whole unit existing in a charge-neutral state. They are Type Ia diamonds. Like graining, H3 centers are created when a fully-formed diamond sits in a high-heat/high-pressure environment. It should come as no surprise, then, that the two defects often occur together. It is the graining that is thought to cause an absorption band at 550 nm which results in orange and orangy yellow colors. After the 480 nm band, H3 defects with plastic deformation is the second most frequent cause of a primarily orange color.
Finally, an orange hue can sometimes come from yet another nitrogen configuration called a nitrogen-vacancy defect (NV centers). NV centers are comprised of a single nitrogen atom sitting next to a vacancy existing in a neutral charge state. Photoluminescence analysis of gems with NV centers shows peaks at 575 nm and 637 nm.
Orange Diamond Trade Names
Trade names are words that are used by tradespeople which are not standard terms like the GIA's Colored Diamond Color Grading System. Often the use of these words is to romanticize the color of a particular gem to help sell it. The two words you will see associated with orange diamonds the most are "fire" and "pumpkin." These words are expressive, but you should never trust a description of a diamond that uses tradenames in place of standard terms. Because the color of a fancy-colored diamond is so important when it comes to value determination, you should always inspect gems personally with good lighting conditions.
Identifying Orange Diamonds
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).
As you gleaned from the previous section, absorption spectra are very important when it comes to orange stones. That broad band at 480 nm which extends to 600 nm is crucial for most pure orange diamonds and scientists have not isolated its exact cause. Orange diamonds with H3 defects also show an additional band at 550 nm that is associated with plastic deformation.
Orange diamonds may fluoresce a number of different colors depending on which defect is responsible for its color.
As a general rule, Type Ib diamonds are usually inert to both longwave and shortwave UV light. If they do fluoresce, it will be a weak yellow, orange, or green color. Gems colored by the 480 nm band may fluoresce a yellow or orange color. This color is usually moderate to strong under longwave UV and weak to moderate under shortwave UV. Alternatively, H3 colored stones may show a dispersed green fluorescent color under both longwave and shortwave UV light.
Interestingly, scientists note that the fluorescence in orange diamonds tends to appear chaotic, perhaps reflecting an unstable growing environment the diamonds formed under.
The inclusions that one may encounter in orange gems are similar to what you might see in colorless diamonds. Dark spots of graphite - which is carbon that did not convert to diamond -may be present. You may also see included crystals of garnet or corundum. If you are looking at a gem that owes some of its color to plastic deformation, you may see internal graining features.
Are There Synthetic Orange Diamonds?
There are two ways that scientists grow diamonds: high pressure, high temperature (HPHT) and chemical vapor deposition (CVD). Today, both methods are used to create manmade orange stones often using NV defects. The first orange HPHT gems were produced in the early 2000s, but there are currently quite a few orange CVD gems on the market. The color of synthetic diamonds is often beautifully uniform throughout the diamond crystal. Note that synthetic diamonds may be treated after their growth to induce/intensify an orange color expression.
Today, one of the hardest challenges facing gemologists is the issue of identifying synthetic diamonds. The newest stones require advanced testing at professional laboratories to recognize them as synthetic. Sometimes, quality can be an indicator of whether or not you are looking at a natural gem. Synthetics tend to have lovely, even color expression and can be grown to large sizes that are unusual in natural stones. When in doubt, send the diamond to a professional lab.
Orange Diamond Enhancements
While NV centers are one of the rarer causes of orange color in natural diamonds, it is a relatively easy defect for scientists to create using combinations of irradiation, annealing, and high pressure/high temperature (HPHT) treatments (note that the HPHT growing process is different than HPHT treatment). These treatments can intensify and even create an orange color in natural stones and the results are stable. Lesser quality treatments include coating the diamond with a colored film or fracture-filling gems with a colored resin or epoxy. Both of these treatments are temporary and are usually easy to see under magnification. Sellers are required to disclose if their inventory has been treated.
Where are Orange Diamonds Found?
The majority of pure and dominantly orange diamonds come from only two places: the Argyle Mine in Western Australia and South Africa. The Argyle is perhaps the most famous diamond mine in the world, and its reputation is well-deserved. The site of ancient continental interaction, Argyle hosts many of the world's best fancy-colored diamonds including pink, red, blue, and orange gems. Unfortunately, Argyle ceased operations in 2020 which leaves South Africa as the primary supplier of pure orange gems worldwide.
Famous Orange Diamonds
The Pumpkin Diamond
This famous 5.54 ct. orange diamond was discovered in central Africa at the end of the twentieth century. The value of the Pumpkin rose quickly over just a few years inflating from 1.3 million dollars in 1997, to being valued at 3 million soon after. Today, it is estimated that the Pumpkin is worth twice that amount. This remarkable diamond is credited with helping to increase the profile of fancy-colored diamonds in general and was, for a time, a part of the Smithsonian Splendor of Diamonds Exhibition.
Fancy-colored diamonds in general tend to be small, often measuring under five carats. However, this gigantic Fancy Vivid Orange stone weighing 14.82 ct. dwarfs its competition. A beautiful gem with VS1 clarity, the Orange sold at auction in 2013 for $2.4 million dollars per carat.
Orange Diamond Sizes
We now know that unmodified orange diamonds are very rare and are usually Type Ib. We also have explored why it is unusual for diamonds to remain Type Ib because, on a molecular level, nitrogen atoms want to find each other and create a Type Ia gem. It should come as no surprise, then, that most pure orange gems are small, usually weighing under six carats.
How to Care for Your Orange Diamond Jewelry
Fortunately, the color of orange diamonds is considered stable. This means that you are free to wear and clean your orange diamonds the same way that you would your colorless gems. Whether you use a gemstone cleaning solution, an ultrasonic machine, or steam, orange diamonds can withstand any conventional cleaning method. See our gemstone jewelry cleaning guide for more recommendations.
Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.
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