Green diamonds are captivating colored diamonds, distinguished by their unique hue. These natural diamonds are formed through specific geological processes, and their vibrant appearance sets them apart from colorless diamonds.
How Green Diamonds Get Their Color
Natural green diamonds acquire their color through natural radiation over millions of years. This radiation causes structural defects within the crystal lattice. When carbon atoms are displaced, they create vacant sites, known as GR1 centers. These defects selectively absorb red light, transmitting green light. While GR1 defects are the most common cause, other defects involving nitrogen, hydrogen, or nickel impurities also contribute to green coloration.
Many natural green diamonds have color concentrated on the surface, forming a “skin” or spots. This surface color often results from exposure to alpha radiation, with limited penetration depth. Diamonds with uniform green color throughout are exceptionally rare, generally forming from more energetic beta or gamma radiation that penetrates deeper. This natural process can be mimicked in laboratories through artificial irradiation treatments.
Their Rarity and Value
Natural green diamonds are among the rarest fancy colored diamonds, less than 0.4% of all diamonds submitted to gemological laboratories. Pure green hues are rarer still. This extreme scarcity is a primary factor contributing to their substantial market value, as only a limited number are introduced into the market each year.
These diamonds are found in specific geographical locations. Historically, significant sources include South America (Brazil and Guyana) and various African countries (South Africa, Angola, Sierra Leone, Zimbabwe). Russia has also yielded some green diamonds, often with a yellowish tint. The Dresden Green, a renowned 41-carat diamond, is believed to have originated from the Golconda mines in India or Brazil.
Green diamond value is influenced by rarity and high collector demand. Carat weight, color intensity, and secondary hues determine its price. Color intensity is graded from Faint Green to Fancy Vivid Green or Fancy Deep Green, with more intense and pure green hues commanding higher prices. Secondary hues, such as yellowish-green, bluish-green, brownish-green, or grayish-green, also affect their value.
Identifying Natural vs. Treated Green Diamonds
Distinguishing natural from treated green diamonds is important for authenticity and value. Artificial irradiation mimics natural radiation, making identification challenging. Gemological laboratories employ advanced testing methods to determine a diamond’s color origin.
Laboratories like the GIA utilize sophisticated techniques including spectroscopy, UV-Vis-NIR absorption analysis, and luminescence testing. These methods analyze defects and optical properties to determine if its color is natural or laboratory-induced. For instance, certain patterns of coloration, such as clouds of blue or green, or specific spectral features, can indicate natural irradiation.
Natural green diamonds receive reputable grading reports from independent gemological laboratories, explicitly stating the natural origin of their color. The GIA provides detailed reports verifying characteristics. Consumers should always seek such certification to ensure authenticity and natural coloration.