Diamonds come in a wide variety of colors, from colorless to yellow, brown, pink, blue, green, and more. The most common diamond color is colorless or white diamonds. However, some diamond colors are much rarer and more valuable. In this article, we’ll examine the least common diamond colors and what makes them so unique.
What Determines Diamond Color?
A diamond’s color is determined by the presence or absence of trace elements and structural defects in its crystal structure. Here are some of the main factors that influence diamond color:
– Nitrogen – This is the most common trace element in diamonds. Too much nitrogen causes a yellow or brown tint. No nitrogen results in a colorless diamond.
– Boron – This element produces blue diamonds. The more boron present, the stronger the blue color.
– Structural defects – These can give diamonds a pink, red, purple, or brown hue depending on how light is absorbed.
– Radiation exposure – Diamonds with radiation damage take on a green color. Natural green diamonds are extremely rare.
– Chemical vapors – Exposure to hydrogen or nickel during formation leads to rare orange or gray diamonds.
So in summary, it takes very specific conditions to produce diamonds in colors outside the normal colorless to yellow/brown range. Next we’ll look at some of these rare diamond colors.
Natural Red Diamonds
Natural red diamonds are perhaps the rarest diamond color in existence. They account for less than 0.1% of mined diamonds. The vibrant red color comes from structural defects in the crystal lattice. The more intense the defects, the deeper the red color.
Red diamonds typically come from just a handful of mines in the world, such as Argyle in Australia and Golconda in India. The Argyle mine, famous for its pink and red diamonds, shut down operations in 2020 after exhausting its supply. This has made natural red diamonds even more scarce.
The rarity and beauty of red diamonds means they are some of the most expensive diamonds in the world. A 1 carat red diamond can easily cost over $2 million. In 2017, the 59.6 carat CTF Pink Star sold for a record $71 million at auction.
While true natural reds are almost impossible to find, treated diamonds with artificial irradiation are more common. However, these lack the value of untouched natural red diamonds.
Green Diamonds
Natural green diamonds occur in two main varieties – those with a green radiation hue and the even rarer natural green with boron impurities.
Radiation induced greens result from prolonged exposure to radioactivity, usually from naturally occurring uranium deposits. This causes structural damage that gives the diamond a greenish cast. These green diamonds are typically light in color. Famous diamonds like the Dresden Green and Ocean Dream are examples of natural radiation green diamonds.
The extremely rare boron-containing green diamonds have an intense grass green color similar to emerald. There is only a handful known to exist. The most famous is the 5.03 carat Hope Diamond in the Smithsonian Museum. Researchers theorize that unique conditions are needed for boron to be incorporated in the diamond’s structure.
Overall, natural green diamonds comprise less than 0.1% of diamonds, making them highly sought after. Like other fancy colors, green diamond prices skyrocket for more saturated hues. The Ocean Dream 5.51 carat radiant cut sold for over $10 million in 2017.
Blue Diamonds
Blue is another exceptionally rare diamond color, occurring in less than 0.1% of diamonds. The primary cause of blue color is the presence of boron during crystal formation. Traces of boron influence light absorption to give blue hues. The more boron, the stronger the blue color.
One famous example is the Hope Diamond, which exhibits a rare grayish-blue tone. Other natural blue diamonds can range from light blue to vivid blue. Blue diamond prices per carat often exceed those of colorless diamonds. The 14.62 carat Oppenheimer Blue sold for a staggering $57 million in 2016.
A few blue diamonds like the Hope Diamond exhibit a rare phosphorescent glow effect after exposure to UV light. This effect is linked to nitrogen-boron interactions in the crystal lattice.
Beyond these ultra rare natural blue diamonds, there are more common treated blues created by irradiation and heating. However, synthetic blue diamonds have far less value compared to untreated natural blue diamonds.
Black Diamonds
Black diamonds, also known as carbonado diamonds, are another exceptionally unique diamond variety. True black diamonds do not actually absorb all light, but transmit such a small amount that they appear black to the human eye.
This extreme darkness is attributed to black diamonds’ polycrystalline structure containing millions of tiny crystal grains. Light loses intensity when passing through all these interfaces, causing the black color.
Black diamonds comprise around 2% of natural diamonds. Famous black diamonds include the Black Orlov, the Spirit of de Grisogono, and the Amsterdam Diamond. Owing to their mystique, black diamonds typically sell for higher prices than lighter diamonds. A black diamond engagement ring makes a striking statement.
Pink Diamonds
Pink is one of the rarest diamond colors, occurring in about 0.1% of natural diamonds. The pink color results from structural crystal defects that absorb blue light, causing a pink hue. The more intense the pink, the higher the price per carat.
Many famous pink diamonds originate from the Argyle mine in Australia, including the Pink Star, the Argyle Pink Jubilee, and the Williamson Pink. The Argyle mine was responsible for 90% of the world’s pink diamond production, so its closure in 2020 makes natural pink diamonds even more scarce.
Pink diamonds frequently sell for over $1 million per carat. In 2017, the 59.6 carat Pink Star sold for a record $71 million at auction. This makes pink diamonds one of the most valuable diamond colors based on price per carat.
Gray Diamonds
Gray is one of the least common diamond colors, with even diamond sellers rarely encountering a true gray. These diamonds get their smoky gray color from exposure to hydrogen and nickel during formation. The gases deposit into gaps in the crystal structure, influencing light absorption.
The most famous gray diamond is the Hope Diamond, weighing 45.52 carats. Gray diamonds larger than one carat are exceptionally rare. There are also darker gray diamonds mined in the Central African Republic that exhibit an almost black color. However, lighter grays are more common.
Gray diamonds are prized for their steely sheen and industrial vibe. When cut with sparkling facets, gray diamonds exhibit a brilliant metallic shine. Their color distinction drives prices above colorless diamonds. But gray diamonds are still less pricey than more vibrant pinks, blues, and yellows.
Orange Diamonds
Natural orange diamonds are exceptionally rare, with just a few sources worldwide. The intense orange color is linked to nitrogen impurities and structural defects. The most famous is the Pumpkin Diamond unearthed at South Africa’s Orange River mine. At 5.54 carats, it’s one of the world’s largest known orange diamonds.
Beyond these natural orange diamonds, treated diamonds with artificial irradiation are more readily available. Here, the orange color results from lab irradiation and heating. However, naturally occurring orange diamonds are far more valuable.
In 2016, the 14.82 carat Intense Orangy Pink diamond sold for a staggering $35 million at Christie’s – the highest per-carat price ever for an orange diamond. This demonstrates the tremendous demand for this exceptionally rare color.
Purple Diamonds
Natural purple diamonds belong to an extremely rare diamond color group referred to as “fancy vivid.” The bright purple hue forms due to structural defects and the presence of hydrogen during crystal formation. These conditions disrupt the diamond’s light absorption to produce purplish and pinkish hues.
Some famous natural purple diamonds include:
– The Supernova Ring, a massive 53.6 carat diamond valued at over $100 million.
– The 31.01 carat Wittelsbach-Graff Diamond, sold for $24 million in 2008.
– The Royal Purple Heart Diamond, a 7.34 carat heart cut stone sold in 2018 for $8.8 million.
Purple diamonds larger than one carat are scarce and command huge premiums at auction. Their natural beauty and mystique makes them one of the most expensive diamond colors per carat.
Yellow Diamonds
Yellow is one of the most common diamond colors, occurring in diamonds with detectable nitrogen impurities. However, vivid “Canary” yellow diamonds are quite rare, accounting for under 0.1% of natural diamonds.
The intensity of the yellow color depends on how much nitrogen is present. While pale yellows are somewhat common, vivid yellows over 1 carat are exceptionally rare. Two famous examples include:
| Diamond | Carat | Price |
|---|---|---|
| De Beers Diamond | 234.65 | $18 million |
| Allnatt Diamond | 101.29 | $3.1 million |
As the table shows, large vivid yellow diamonds over 100 carats fetch millions at auctions. Their immense size and dazzling color has tremendous appeal to collectors.
Chameleon Diamonds
“Chameleon” diamonds exhibit an extremely rare color change phenomenon. In different lighting conditions, they shift between various colors like yellow, green, blue, pink, orange, and brown. This color instability comes from structural anomalies that influence light absorption inconsistently.
Less than 30 chameleon diamonds have ever been discovered. One famous example is the Hope Diamond, which shifts from steely blue to purple under UV light. Other chameleon diamonds change between green and yellow or yellowish-brown hues.
Chameleon diamonds over 1 carat are virtually unheard of. In 2018, a rare 3.47 carat chameleon diamond sold for nearly $4 million at Christie’s Geneva. The allure of their optical magic makes chameleon diamonds immensely desirable to collectors.
Conclusion
While colorless diamonds are the most common, fancy color diamonds are far more rare and valuable. Unique trace elements and conditions during formation lead to these prized colored varieties. Pink, red, and blue are some of the rarest diamond colors, along with unique chameleons and grays. Even pale shades of these colors command huge premiums for their beauty and rarity.
Among collectors, the rarest diamonds are those exhibiting the most intense, vivid colors. Larger sizes over 1 carat magnify the appeal and value exponentially. As mining depletes natural supplies, these spectacular fancy color diamonds will only become more prized over time. Their splendor and scarcity puts them atop the wishlists of diamond aficionados worldwide.