How Colored Diamonds Get Their Hue
Discover the natural science behind colored diamonds, from vivid blues to fiery oranges, and what makes these rare gems so uniquely valuable.
D iamonds and colored diamonds occur in an array of hues – from pure whites and soft pinks and blues to brilliant hues of purple and red. No matter the color, each stone possesses a unique composition of chemical elements that have the power to dictate rarity, value and desirability.
While the quintessential clear diamond remains the most sought-after iteration, the presence of minute impurities and structural anomalies is what creates their saturated, colorful counterparts, “Fancy Diamonds”. It comes down to the intricate interplay of a diamond’s atomic structure and chemical composition, determined when a diamond is initially forged – deep within the Earth’s crust and under extreme heat and pressure. Atoms of nitrogen, boron, or even structural defects can interact with the diamond's crystal lattice structure to produce a spectrum of breathtaking shades – canary yellows, royal blues, enigmatic pinks, and more.
White Diamonds
White diamonds are the most common hue, falling into the largest color spectrum on the Diamond Grading Scale, which begins with “D” color, meaning totally colorless, and ending with “Z” color, which is pale yellow or brown.
The variable in this spectrum is the element nitrogen – a D color diamond has no nitrogen (or only a microscopic amount) nor any other element present. The larger the amount of nitrogen present, the more the color increases, thus moving the diamond along the color spectrum.
The vast majority of white diamonds mined today have a large content of nitrogen, which classifies them towards the lower end of the color scale. Diamonds that fall within the D–F color range are rare, and therefore will typically command a higher price than those towards the end of the spectrum.
Yellow Diamonds
Yellow diamonds owe their hue to the presence of nitrogen impurities within their carbon crystal structure. These nitrogen atoms alter the way the diamond interacts with light, absorbing the blue part of the visible spectrum and allowing the yellow color to dominate. While many diamonds contain some nitrogen, it is the quantity and specific arrangement of these atoms that determine whether a diamond will exhibit a true yellow color or remain nearly colorless, with just a tinge of yellowish hue peeking through.
When nitrogen is present in significant amounts, a diamond transcends the typical color grading scale of D to Z and becomes classified as a fancy colored diamond. These fancy yellow diamonds are graded on a spectrum from Fancy Light to Fancy Vivid, with the intensity of the yellow color directly influencing their value. Despite their rarity, fancy yellow diamonds are more common than other fancy colored diamonds, offering a relatively affordable entry into the world of colored diamonds.
Yellow
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Green Diamonds
Green diamonds are among the rarest of all fancy colored diamonds and owe their distinctive hue to natural radiation exposure that occurs deep within the Earth over millions of years. Unlike other colored diamonds that gain their color from chemical impurities, green diamonds get their coloration from atomic displacements caused by radiation. This process typically affects only the outermost layers of the diamond, which is why fully saturated green diamonds with uniform color throughout are exceptionally rare and prized.
These unique gems often exhibit secondary hues, such as yellow or gray, and are typically found with descriptors like “grayish yellowish green.” One such example is this Fancy Deep Grayish Yellowish Green diamond ring, featuring a 16.41 carat cushion modified brilliant-cut stone, flanked by cushion-shaped diamonds, which sold for 406,400 CHF at Sotheby’s High Jewelry auction in May 2025. Its striking hue and impressive carat weight made it a standout among collectors of rare colored diamonds.
Brown Diamonds
Brown diamonds are the most commonly found natural colored diamonds, yet they are among the most misunderstood. Their earthy hues range from champagne and cognac to rich, deep tones with orange or reddish modifiers. Unlike yellow or blue diamonds, which get their color from trace elements, brown diamonds owe their coloration to structural defects in the crystal lattice—specifically, distortions caused by pressure during formation.
Despite their abundance, certain brown diamonds can be incredibly valuable, particularly when they are large, vivid in color, and paired with unique design elements. A spectacular example is “The Earth Star”, a pendant designed by David Webb, featuring a Fancy Deep Orange-Brown diamond weighing 111.59 carats, set within a carved azurmalachite frame and accented with brilliant-cut diamonds. This remarkable piece fetched 482,600 CHF at Sotheby’s High Jewelry auction in May 2025, highlighting how size, color intensity, and artistry can elevate a brown diamond’s value.
Orange Diamonds
Orange diamonds are exceptionally rare and derive their fiery hue from a unique interaction between nitrogen atoms in the diamond's lattice. Unlike yellow diamonds, where nitrogen is typically clustered, the orange hue is believed to result from isolated nitrogen atoms absorbing blue and yellow light, leaving behind a brilliant orange appearance. True pure orange diamonds, sometimes referred to as "pumpkin diamonds," are exceedingly scarce, and most orange diamonds exhibit modifying hues like yellow or brown.
One notable example is the Fancy Vivid Yellowish Orange diamond ring titled “Havana” by Boodles. This piece features a 3.03 carat pear-shaped diamond encased in a rock crystal and enamel setting, bordered by brilliant-cut diamonds. The striking design and vivid color achieved a final price of 508,000 CHF in May 2025, underscoring the high demand for rare orange diamonds in contemporary fine jewelry.
Blue Diamonds
Blue diamonds derive their color from boron impurities in the crystalline structure. Boron absorbs yellow light and reflects blue, with varying concentrations creating different blue shades. Unlike most diamonds, which form closer to the Earth’s surface, blue diamonds originate from extreme depths – up to four times deeper. This deep formation process involves subduction, where the Earth’s tectonic plates move and bring blue diamonds closer to the surface over millions of years.
The famed Hope Diamond is a prime example of these extraordinary gems. Formed one hundred miles beneath the Earth’s surface, this 45.52 carat stone was carried upward by a volcanic eruption more than a billion years ago. It is a window to the past, brimming with rich history and fascinating provenance. Study of this particular blue diamond has revealed significant insights into the origin of blue diamonds, including how boron from ancient sea floors may have been transported to the surface.
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Pink, Red & Other Colored Diamonds
Pink and red diamonds stand apart from other colored diamonds. While most colored diamonds owe their hues to trace elements or impurities – such as nitrogen in yellow diamonds and boron in blue diamonds – pink diamonds gain their color from a phenomenon called plastic deformation. This process involves extreme pressure beyond what creates any other diamond, which distorts the diamond's crystal lattice and causes it to reflect red light. The more pronounced the deformation, the richer the pink hue. The strongest and deepest pink hues will appear red, and only 30 such natural red diamonds are known to exist in the world. Many pink or red diamonds do not survive this intense formation process and those that do are typically smaller in size. It is incredibly difficult and exceptionally rare to achieve high clarity and large carat sizes in these gems. The Williamson Pink Star, a cushion cut fancy vivid pink diamond weighing 11.15 carats, sold at a record-breaking $57.7 million at Sotheby’s in Hong Kong in 2022, setting an exceptional new world record price per carat for any diamond or gemstone and becoming the second most valuable jewel or gemstone ever sold at auction.
Even among these exceptionally rare red diamonds, few reach significant carat weights, making them some of the most elusive and sought-after gems in the world. The square emerald-cut Fancy Brown-Red diamond known as The Red Diamond, weighing 5.05 carats, is a remarkable example of this extraordinary category. Sotheby’s was honored to present this rare gem as part of its exhibition, Beyond the World’s Rarest Diamonds, in April 2025.
The majority of pink diamonds that exist today were sourced from the Argyle mine, located in northwestern Australia. Argyle pinks are particularly prized for their vibrant color saturation, attributed to densely-packed graining planes that emit a strong pink hue. In contrast, pink diamonds from other sources generally have lighter colors due to fewer and less distinct pink grainings. With the Argyle mine's closure in 2020, the rarity and desirability of these pink diamonds continue to rise, marking them as some of the most coveted gems in the world.
Colored diamonds are a testament to the remarkable forces of nature, where subtle chemical variations and structural anomalies give rise to an extraordinary spectrum of hues. From the nitrogen-induced yellows to the boron-infused blues and the pressure-born pinks and reds, each diamond tells a unique geological story, making them some of the most fascinating and coveted gemstones in the world.
As demand for these rare treasures continues to grow, their allure remains timeless—whether as a collector’s piece or a symbol of personal expression. With Sotheby’s offering an exquisite selection of these vibrant gems, the opportunity to own a piece of nature’s artistry has never been more compelling.
