Fancy colored diamonds exhibit a mesmerizing range of hues, with purple diamonds being one of the most profoundly rare color groups. While yellow and brown diamonds are comparatively common, stones exhibiting natural purple or violet saturation are found in minuscule quantities globally. This extreme scarcity places purple diamonds in the uppermost tier of colored gems, second in rarity only to the elusive red diamond. Their rarity stems from specific geological conditions and a supply volume that is statistically insignificant compared to overall diamond production.
Statistical Scarcity of Purple Diamonds
The annual volume of purple diamonds recovered defines their rarity in the jewelry market. Less than one carat of every 10,000 carats of rough diamonds mined is considered gem-quality fancy colored. Natural purple diamonds account for only a tiny fraction of this, estimated to make up just two-tenths of one percent (0.2%) of all fancy colored diamonds brought to market.
This scarcity is compounded because most stones display a modifying color, such as pink, gray, or brown, which affects the overall hue. Data collected by the Gemological Institute of America (GIA) showed that stones graded as unmodified, pure purple accounted for only 0.05% of a large sample of pink-red-purple diamonds. Finding a stone with strong color saturation, like Fancy Intense or Fancy Vivid Purple, is exponentially more difficult and results in a substantial premium.
The Unique Geological Cause of the Color
The purple color in diamonds does not typically arise from common chemical impurities like nitrogen or boron, which cause yellow and blue hues, respectively. Instead, the color is primarily a result of structural defects within the crystal lattice, known as plastic deformation. This deformation occurs when the diamond crystal is subjected to immense pressure and heat during its deep-earth formation or transport to the surface.
This geological stress causes slippage along the atomic planes, creating narrow bands of color known as “graining” or lamellae. In purple diamonds, this structural distortion is often combined with a high concentration of hydrogen impurities trapped within the lattice structure. The interaction between these hydrogen-related defects and the stress-induced graining selectively absorbs light to produce the distinct purple or violet hue.
Primary Mining Locations
The global supply of natural purple diamonds has historically been concentrated in a very limited number of geographical sites. The most significant source was the Argyle Mine in Western Australia, known for producing a spectrum of colored diamonds, including violet-to-purple hues. The Argyle deposit was unique in its geology, and its closure in November 2020 has further restricted the global availability of these stones.
While Argyle was the dominant producer, purple diamonds are also found sporadically in other locations. The Siberian region of Russia, particularly the kimberlite pipes of the Mir field, has historically yielded a small number of purple crystals. Occasional finds have also been reported in South Africa and Brazil, though these sources are minor contributors.
Distinguishing Natural and Treated Purple Hues
Given the rarity and high value of natural purple diamonds, the market contains stones that have undergone color enhancement or are laboratory-grown. Distinguishing a naturally colored stone from a treated one requires advanced gemological testing for verification.
In a natural purple diamond, the color is visually observed to be concentrated along the internal deformation lamellae or graining, appearing in distinct planes within the crystal. Conversely, color-treated diamonds, often enhanced through irradiation or High-Pressure/High-Temperature (HPHT) processes, typically exhibit a color that is evenly distributed throughout the stone or confined to specific growth zones. Gemological laboratories, such as the GIA, use specialized equipment to detect unique spectroscopic signatures that identify the color’s origin. Natural purple diamonds often show a specific hydrogen-related peak in their infrared spectrum, a feature that cannot be replicated by current color enhancement methods.