By Mitch Rice
Diamonds are the most famous and most beloved gemstones. They are the centerpiece of unique engagement rings, elegant necklaces, earrings and other high-end jewelry. In addition to the classic transparent color, diamonds of different shades are much rarer. Colored stones are called “fancy”. Behind the windows of jewelry stores, one can find gray-silver, blue, orange, pink, green, and champagne-colored diamonds on velvet liners.
Yellow and brown-cognac diamonds are the most common, while red or purple are the rarest. Currently, there is only one known deposit where they are mined: Argyle in Australia. Black stones do not belong to the category of fantasy stones. They have a distinctive coloring due to the presence of graphite. It is opaque, so it is impossible to judge the clarity of such a diamond when looking at it visually.
There is still a great demand for transparent diamonds, but colored diamonds, being rare, attract more and more attention. Experts develop new technologies that will make it possible to change a stone’s color artificially. The buyer must be warned about the “prehistory” of this gem.
What affects the color and hue of a stone?
Changes in the color of a diamond may occur only under the influence of natural factors. The process of crystallization takes a long time. Diamonds are formed in the depths of the Earth’s mantle, several hundred kilometers deep. There is high pressure and incredible heat. If carbon is heated to such temperatures on the Earth’s surface, the substance will simply burn up, and no miraculous transformation into the hardest mineral will occur. It is the same carbon as in the furnace, which has a slightly different arrangement of atoms. There is no free oxygen at depth, so the diamond cannot burn here. Temperature and pressure fluctuations, radioactive radiation, nearby dust particles, and impurities of other chemical elements can change the color of a diamond.
Changes in the crystal lattice under pressure can produce a rare red diamond. The presence of boron produces a blue hue, while nitrogen produces orange, yellow, or brown. The radioactive radiation of the mineral in the depths of the Earth contributes to the appearance of green, the second rarest color among diamonds.
The colors in fancy diamonds can have varying degrees of saturation. The purity of the hue depends on the “natural data” of the stone and how it is treated. There are methods for making the color richer by artificial means. Generally speaking, diamonds are available in nine gradations of color saturation, from a very slight hue to a very intense, fancy color.
How are diamonds graded in color?
There are several systems for assessing the quality of minerals, the most popular of which is the “4Cs”. This analysis method has been developed at the Gemological Institute in the United States, where the main evaluation procedure is carried out.
How do I know the color assigned to a diamond?
For the buyer’s convenience, special tables were created to convert the data from one grading system into another. All of the identifiers and grades assigned to a specimen are written in the form of an alphanumeric code. This designation is unique to each stone, much like a person’s passport data or a car license plate number.
The code is recorded in the organization’s registry that performed the appraisal. The same alphanumeric code is used on a diamond’s tag, which is a document certifying its quality.
Data and information are provided for informational purposes only, and are not intended for investment, medical or other purposes.
