Green diamonds are a captivating reality, a unique and rare occurrence in the world of gemstones. Unlike colorless diamonds, these verdant treasures possess a distinct green hue. Their existence is a testament to the Earth’s geological processes, a natural phenomenon that fascinates collectors and enthusiasts alike.
The Science Behind Their Color
Natural green diamonds acquire their green color through prolonged exposure to natural radiation within the Earth. This process typically occurs when diamonds come into contact with radioactive minerals like uranium and thorium. The radiation emitted by these elements causes structural changes within the diamond’s crystal lattice.
Specifically, it knocks carbon atoms out of their original positions, creating vacant sites known as color centers. These lattice defects selectively absorb certain wavelengths of light, primarily red and blue, allowing only the green spectrum to be reflected. While alpha radiation often results in a shallow green “skin” on the diamond’s surface, higher-energy beta or gamma radiation can penetrate deeper, leading to a more uniform green body color.
Natural vs. Treated Green Diamonds
Distinguishing natural from color-treated green diamonds is a significant aspect of gemology. Treatments replicate the appearance of rare natural green diamonds, making them more accessible. The most common method for treating diamonds to achieve a green color involves laboratory irradiation, exposing diamonds to high-energy particles like electrons, neutrons, or gamma rays. This artificial process creates color centers within the diamond’s structure, similar to natural radiation.
A key difference often lies in the color distribution. Natural green diamonds frequently exhibit concentrated patches of green color, sometimes called “radiation stains” or a “green skin,” especially on rough surfaces. Treated green diamonds often show a more uniform color throughout, though some rare natural diamonds can also display even coloration.
Gemologists look for specific patterns of color zoning or unevenness to determine a diamond’s origin. To aid identification, some diamond cutters intentionally leave a small unpolished area, called a “natural,” on the girdle, which can reveal the original radiation stains. For definitive authentication, gemological certification from reputable laboratories like the Gemological Institute of America (GIA) is essential to determine if the color is natural or treated.
Rarity and Market Value
Natural green diamonds are exceptionally rare and highly sought after in the gem world. They comprise less than 0.1% of fancy colored diamonds graded by major gemological laboratories. This scarcity contributes to their high market value.
Several factors influence a natural green diamond’s value, including its color intensity, purity of hue, size, and clarity. The most prized green diamonds are those with a pure, vibrant green hue, often graded “Fancy Vivid Green.” Diamonds with secondary colors, such as yellowish-green or grayish-green, are more common and less expensive than pure green stones.
Large, high-clarity natural green diamonds command substantial auction prices. For instance, the 5.03-carat “Aurora Green” diamond, a Fancy Vivid Green, sold for $16.8 million in 2016, setting a world record for a green diamond. Prices for a 1-carat natural green diamond can range from $50,000 to $100,000 for a “Fancy Green” to over $300,000 for a “Fancy Vivid Green.”