Purple Diamond Value, Price, and Jewelry Information

Purple Diamond Value

Purple diamonds are rare and large purple diamonds are almost non-existent. As is the law of supply and demand, when supply is low, the demand (and thus value) increases accordingly. Interestingly, purple diamonds that express a secondary pink hue also command values in the millions of dollars per carat. It is, in fact, a very desirable combination. This is not true of some other combinations like purple with brown or purple with gray.

Compounding the issue, if a buyer specifically wants a transparent purple gem, they have other options like amethysts which are far more affordable, can be larger in size, are abundant enough to create matched suites, and are more deeply colored.

Purple Diamond Grading

Like many of the other fancy-colored diamond varieties, purple gems are categorized according to the nine-step system developed by the GIA called the Colored Diamond Color Grading System. From weakest to most powerful color expression, the nine steps are: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Dark, Fancy Deep, and Fancy Vivid. As mentioned, purple diamonds tend to fall toward the beginning of this list and rarely are dark or saturated enough to earn the last several grades.

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Does Purple Diamond Make a Good Jewelry Stone?

Diamonds are famous for being the hardest naturally-occurring mineral on Earth. Fortunately, the cause of purple hues does not affect the overall durability of the gem. Gemologists break down the concept of durability into three subcategories: hardness, stability, and toughness. We know that diamonds are supremely hard and that their surface can only be scratched by another diamond. This is why they have become the stone of choice for engagement rings. Further, diamonds are quite stable, meaning that they are not harmed by common irritants like light, heat, and everyday chemicals. The weakest durability score of a diamond is its toughness. Toughness describes how vulnerable a gem is to chipping. Diamonds can chip if hit with enough force and its girdle edge, corners, and points are most at risk.

There is a quiet elegance to purple fancy-colored diamonds which can lead to them being overshadowed by other, flashier, diamond colors like red, violet, and, especially, pink. It does not help that most of the purple diamonds that are unearthed don't have bright, highly saturated hues and are often paired with unattractive gray or brown modifying colors. Pure purple gems are so rare that it is estimated that there are less than one hundred in circulation today.

Matching Purple Diamonds

Finding matched sets of diamonds is a tall task for many of the fancy hues, purple included. With so few pure purple stones out there, identifying multiple gems that have similar color, cut, clarity, and carat weight is next to impossible. It is easier to find complementary gems with a blended color. However, as the color of synthetic gems may be grown so consistently, it is relatively easy to create identical diamonds.

The History of Purple Diamond

Because of their relative anonymity and continued lack of general interest by the public, the history of purple diamonds is not as well documented as some of the other colors. For example, archeological evidence shows that brown diamonds were used as jewelry more than 2,000 years ago. We also have written records stating that the world's first pink diamonds came from India and were introduced to Western Europe in the seventeenth century by a famous gem trader. Unfortunately, such information for purple diamonds is not readily available. In fact, a web search for historical context will yield results for other colors like violet, skipping over purple completely. This is a shame because purple diamonds can be absolutely beautiful and deserve to shine in their own right.

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Purple Diamond Color

As you now know, pure purple gems are very rare. More often, their color is paired with undertones of gray or brown. Neither of these modifying colors is considered desirable because they subtract from the vibrancy of the purple color. However, some purple gems are paired with a pink hue which is a very highly sought-after combination. These gems regularly sell through exclusive auctions.

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Are Violet and Purple the Same Colors?

For some reason, when researching purple diamonds, you are likely going to come across sources that mention both purple and violet in the same breath. It is important to know that they are two entirely separate hues with different coloration factors. On the color wheel, purple is a warmer color that sits adjacent to red while cooler violet is next to blue. While purple and violet are situated next to each other, the GIA does not recognize a blended purple/violet hue. They are always separate.

What Causes Purple Diamond Color?

As described in detail in a Gems & Gemology article from 2018 by S. Eaton-Magaña et al., the cause of purple color in diamonds is similar to the cause of red, pink, and brown hues which explains why the color of so many gems is a combination of those hues. Specifically, it is post-growth natural plastic deformation that creates atomic slippage on a plane parallel to the octahedral plane to create deformation lamellae, also called "graining." To understand this concept, let's take a closer look at the diamond crystal.

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Viewed straight down as seen on the top photo, this 0.40 ct. modified cushion-cut Fancy Intense Pink-Purple diamond seems to have an even color expression. However, if you rotate the gem slightly, you can easily see the lines of colored graining which give the gem its color.

In its purest form, the diamond crystal is made of carbon atoms that are tightly interlocked together in a perfect cubic formation. It takes a lot of heat and pressure to force carbon atoms to bind like this, but the resulting crystal lattice is incredibly strong. If you rotate the cubic structure to look at the individual atoms in formation, you will find an angle of vulnerability along the octahedral plane, otherwise known as the {111} plane. Here the force holding the atoms together is a bit weaker and it is along this plane of weakness that the atoms may slip if they are exposed at length to extra pressure and heat, specifically more than 900^°C, after the gem has matured.

Slipping is not breaking. The diamond crystal remains intact, but a very narrow band parallel to that octahedral plane called a "deformation lamella" has been created where atoms are out of place and some locations where carbon atoms should be are left vacant. You may hear this angle called the "glide plane" and it is due to this irregularity that a purple color is created in an otherwise colorless gem.

When such slippage happens in a diamond, it occurs multiple times. This means that purple diamonds play host to many lamellae, rather than just one or two. Generally speaking, the more bands inside the crystal, the darker the color. It should be noted here that bands don't need to be regularly spaced out. Rather, some areas may have an abundance of lamellae while other regions host only a few. Additionally, these bands are quite thin, some measuring a mere 0.1 mm thick. If you hold the diamond so that you are looking down on the octahedral plane, the diamond crystal appears uniformly purple because you are looking down on the surface of the graining pattern. Because of this, cutters will choose to orient the gem so that looking at the table facet makes the gem's color appear smooth.

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There is another factor that can play into this and that is the presence of nitrogen. Nitrogen is the most common impurity seen in diamonds and about 98% of all mined stones have some measurable nitrogen interspersed in their crystal lattice. The presence of nitrogen, itself, doesn't cause a purple hue to be expressed, however, because the atoms are a different size than carbon atoms, wherever they sit weakens the strength of the crystal lattice in that immediate area. These places are especially vulnerable to natural plastic deformation so lamellae will often occur where nitrogen is present.

There are several types of diamonds that have to do with whether or not they have nitrogen. Type I diamonds have nitrogen impurities and make up about 98% of all mined diamonds. In locations where the nitrogen atoms are aggregated together, that particular spot is called a "defect center" and the diamonds that host these centers are categorized as a Type Ia. If the nitrogen atoms are spread out on their own, the gem is a Type Ib. Type II diamonds have no nitrogen. Most purple diamonds are Type I.

Further focusing on Type Ia diamonds, if a defect center inside the gem consists of two nitrogen atoms paired up, that center is classified as Type IaA. If, instead, the nitrogen center is a cluster of four atoms surrounding a vacancy where a carbon atom should be, that defect center is called a Type IaB.

Bear in mind, diamonds will have a mixture of both Type IaA and Type IaB characteristics. When Type IaA centers outnumber Type IaB, the diamond is classified as Type IaA and the colored lamellae are more neatly arranged. The graining pattern of Type IaA tends to be distinct while the body of the diamond crystal is colorless. If you were to tilt one of these stones to view the octahedral plane under magnification, you can observe the hue concentrated in parallel bands. These gems also tend to be deeply colored. If, alternatively, Type IaB centers dominate, the gem is called Type IaB and the purple color won't be as restricted to the graining, the general appearance of the color is messier, and the color likely won't be very strong.

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According to S. Eaton-Magaña et al., the vast majority of purple diamonds they examined were Type IaA dominant with more than 150 ppm nitrogen. That being said, they found that the concentration of nitrogen did not alter the purple color expression. That confirms that it is the graining, not the nitrogen directly, that causes purple expression. Also, the color of gems with higher levels of nitrogen was pinker. It is worth mentioning that the Australian, Namibian, and Venezuelan purple gems examined by S. Eaton-Magaña et al. tended to be Type IaB dominant while the Siberian stones were mostly Type IaA.

Now for some exceptional cases. There are a few rare Type IaB diamonds, as well as the very unusual Type IIa purple diamonds, that may not show graining at all. These may have purple hue distributed evenly through the gem. Additionally, some select Type IIa gems will show graining similar to what Type IaB express. These, however, are atypical examples.

Trade Names for Purple Diamonds

Purple diamonds are similar to brown diamonds in that sellers may use a wide range of unofficial descriptive words to describe their gems. You may see gems listed using terms like "lavender," "lilac," "grape," and "mauve" just to name a few. These words are not standardized like the GIA grading system is, so be sure that you take a good look at the stone itself under good lighting conditions to determine its actual color. It is never a good idea to buy any fancy-colored diamond based on an informal color description.

Identifying Purple 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).

Absorption Spectrum

An examination of the visible spectra of purple, red, pink, and brown diamonds will reveal a broad absorption band centered at 550 nm. In purple and pink/purple diamonds specifically, the 550 nm band is shifted slightly toward the longer wavelengths, allowing more blue to be transmitted with red which is what gives us that beautiful purple color. To be exact, this band in purple diamonds centers around 555-560 nm and is about 70-100 nm wide. The presence of the 550 nm band has been correlated with natural plastic deformation, however, its exact cause has yet to be proven.

While scientists are still investigating why that 550 nm band is shifted in purple stones, they do know that both N3 centers (which reveal themselves in a peak at 415 nm) and H3 centers (which can be seen at 503 nm) play a role in how that 550 nm band makes pink, red, brown, and purple colors. N3 centers are defined as three nitrogen atoms surrounding a vacancy while H3 centers are two nitrogen atoms flanking a vacant space that express a neutral charge state. Pure purple diamonds overall tend to have a low concentration of nitrogen and often do not show a significant presence of either defect center in their spectra while about half of the pinkish purple diamonds examined by S. Eaton-Magaña et al. did show both N3 and H3 peaks.

Fluorescence

Purple diamonds may not fluoresce under longwave UV light at all, but, if they do, there are two options. About a third of purple diamonds will have a weak yellow response while another third will show a weak blue reaction.

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Inclusions and Other Internal Features

Because purple diamonds form under the same conditions that colorless diamonds do, their inclusions are typically consistent with each other. You can definitely expect to see dark graphite inclusions which are carbon impurities that failed to convert to diamond. These may be expressed in clouds containing lots of tiny graphite specs or larger individual impurities. Also, look for small crystals made of garnet or corundum. When looking at a grading report, note that the accompanying plot will not map the graining patterns. Rather, there will be a written note stating its presence.

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Are There Synthetic Purple Diamonds?

While most natural purple diamonds are colored by graining as the result of sheer stress imposed on them after their crystal has formed, both natural diamonds whose color has been altered to show purple as well as synthetic purple diamonds usually owe their color to something else entirely - Nitrogen-Vacancy (NV) Centers. NV centers are thought to be places in the atomic structure of diamonds were a single nitrogen atom sits adjacent to a vacancy where a carbon atom should be. 

NV centers are very rare in natural, unaltered purple diamonds. However, it is relatively easy for scientists to create them by irradiating a stone followed by careful annealing. The vast majority of synthetic purple stones, whether they be grown via the Chemical Vapor Deposition method (CVD) or, more commonly, the high pressure, high temperature (HPHT) technique, also owe their color to NV centers.

Where is Purple Diamond Found?

If you have read any of the other guides for fancy-colored diamonds in our series, it should not be a shock that the first location on our list is the famous Argyle mine located in the Kimberley region of Northwestern Australia. During its operating years of 1983-2020, Argyle was the world's premier source of many fancy-colored diamond species. In particular, they are known for their beautiful reds and pinks and are credited with developing the successful marketing strategy of rebranding brown diamonds to increase their popularity. They also found some lovely purple stones which did not receive nearly the level of attention that the other colors did.

With Argyle now closed, the Siberian Mir kimberlite field in Russia is the best source of purple diamonds in the world, although most of their gems are said to be quite pale. The four mines that excavate this pipe are the Dachnaya, Internationalaya (also spelled Internatsional'naya), Mir, and Sputnik. Unfortunately, these mines have not released a formal breakdown of the percentages of colored diamonds that have been discovered. They have released parcels of diamonds which have included as much as 6% purple stones, but the actual number is almost certainly lower and is veiled in secrecy.

With the many social and political issues surrounding Russia and its natural resources at this time, nothing is certain about the immediate future of their diamonds, fancy-colored or otherwise, on the market. An impending ban on Russian diamonds by the G7 countries may drastically change the market for years to come regardless of the gems contained there.

There are other locations that produce a small number of purple diamonds such as Quebec, Canada. South Africa and the Amazon region in Brazil have yielded individual gems but are not considered reliable sources.

Famous Purple Diamonds

The Royal Purple Heart Diamond

Kicking off our list of important purple gems is the mysterious Royal Purple Heart, reportedly the largest faceted Fancy Vivid purple diamond out there. Weighing an impressive 7.34 cts., it is thought to be a Russian gem. Typically, famous diamonds are named for their host mine or their owners, but, because it is not known who owns this gem or exactly where it came from, it is named simply for its color and shape which is listed as a heart even though it lacks facets creating cleavage between the two lobes. When the stone was examined sometime around 2002, the gemologist noted that there was apparent graining visible through the table facet (something that we will examine in detail below).

The Purple Orchid

This South African diamond has that valuable dual-hued purple/pink color which is graded as Fancy Intense pinkish Purple. The rough crystal of this diamond weighed more than 4 ct. and the final faceted gem weighs 3.37ct. which is an impressive retention rate. In 2014, the Purple Orchid was offered at a Hong Kong show for almost $1.2 million per carat.

The Victorian Orchid

The color of this cushion cut 1.64 ct. gem was graded by the GIA as a Fancy Vivid Purple. For a while in 2016, the Victorian Orchid was on display at the Natural History Museum of Los Angeles County. It is currently set in a custom ring mounting designed by Scott West.

The Supreme Purple Star

When researching significant purple diamonds, you are going to come across this unusual gem that lacks known facts because no official representative has ever actually seen it. Rumored to be a round brilliant weighing somewhere between two to five carats, this gem is said to exhibit both purple and red body colors depending on the lighting conditions. If this is true, it is an entirely unique phenomenon that, for the moment, no one can explain. Ordinarily, a gem without credible and verified information would not make our list, however, the numerous mentions of it online prompted us to include it so that you will have the context if you encounter it in your own searches.

Purple Diamond Sizes

Purple diamond crystals, like many fancy-colored diamond varieties, tend to be quite small. Of the approximately 50 unmodified purple gems analyzed by S. Eaton-Magaña et al., 91% weighed less than two carats.

How to Care for Your Purple Diamond Jewelry

Fortunately, the color of purple diamonds is considered stable. This means that you can wear and clean your jewelry just as you would your colorless diamonds. See our gemstone jewelry cleaning guide for more recommendations.