How Natural Fancy Colored Diamonds Farmed in the Earth

Natural fancy colored diamonds are formed deep within the Earth’s crust under intense heat and pressure over millions of years. The process begins with carbon atoms being subjected to extreme conditions, causing them to crystallize and form diamonds. However, the presence of impurities or trace elements during this formation process gives rise to the vibrant colors seen in fancy colored diamonds.

Diamond Formation Process

  1. Carbon Source: The primary source of carbon for diamond formation is organic material, such as plant and animal remains, which gets buried deep within the Earth’s mantle.
  2. Subduction: Over time, tectonic plate movements cause these organic materials to be subducted deeper into the Earth’s mantle.
  3. Extreme Heat and Pressure: As the organic material descends further into the mantle, it encounters extremely high temperatures (around 900-1,300 degrees Celsius) and pressures (around 725,000-870,000 pounds per square inch). These conditions are essential for diamond formation.
  4. Crystallization: Under these extreme conditions, carbon atoms arrange themselves in a crystal lattice structure, forming diamonds.
  5. Kimberlite or Lamproite Eruptions: Diamonds remain trapped within the Earth’s mantle until volcanic activity occurs. Kimberlite or lamproite magma, which originates from deep within the mantle, carries diamonds to the surface during volcanic eruptions.
  6. Speedy Ascent: The magma containing diamonds rises rapidly towards the surface due to its buoyancy and pressure release. This rapid ascent prevents the diamonds from converting back into graphite, their stable form at surface conditions.
  7. Cooling and Solidification: As the magma reaches shallower depths, it cools and solidifies to form igneous rocks known as kimberlite or lamproite pipes. These pipes often contain diamonds along with other minerals.

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Formation of Fancy Colored Diamonds:

The coloration in fancy colored diamonds is a result of specific impurities or structural defects within the crystal lattice. These impurities can alter the diamond’s absorption and reflection of light, leading to a range of colors. The following are some examples of how different impurities contribute to specific colors:

  1. Nitrogen: The most common impurity in diamonds is nitrogen. When present in large quantities, it imparts a yellow or brown hue to the diamond. However, when nitrogen atoms are arranged in specific configurations, they can create rare and valuable fancy colored diamonds like intense yellow or even orange.
  2. Boron: In contrast to nitrogen, boron impurities can cause diamonds to appear blue. The presence of boron atoms absorbs red and yellow light, resulting in a blue coloration.
  3. Structural Defects: Other fancy colored diamonds derive their hues from structural defects within the crystal lattice. For example, green diamonds may contain natural radiation-induced defects, while pink and red diamonds may have undergone plastic deformation during their formation.

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Mining and Extraction

Once diamond-bearing kimberlite or lamproite pipes are identified through geological surveys, mining operations are initiated to extract the diamonds. The process typically involves the following steps:

  1. Open-Pit Mining: If the diamond deposit is near the surface, open-pit mining is employed. This method involves removing overlying layers of soil and rock to expose the kimberlite or lamproite pipe.
  2. Underground Mining: In cases where the diamond deposit is deeper underground, underground mining techniques are used. This involves creating tunnels and shafts to access the diamond-bearing pipes.
  3. Crushing and Sorting: Once extracted, the kimberlite or lamproite ore is crushed into smaller fragments for further processing. The crushed ore is then sorted using various techniques to separate the diamonds from other minerals.
  4. Diamond Recovery: Several methods are used for diamond recovery, including dense media separation (DMS), X-ray sorting machines, and grease tables. These techniques exploit the differences in density, electrical conductivity, or surface properties of diamonds compared to other minerals.
  5. Final Sorting and Grading: The recovered diamonds are then sorted based on their size, shape, color, and quality. They are evaluated using internationally recognized standards, like the 4Cs (carat weight, color, clarity, and cut).

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