Diamond color

From ArticleWorld

Diamonds are found in numerous colors, but the ideal diamond is colorless and transparent, and therefore extremely rare. Diamonds are often found with impurities and imperfections in shape, which are two reasons why they vary so much in color. However, these colored diamonds are priced according to their hue and intensity of color. For instance, white diamonds are considered to be much less valuable if the intensity of the yellow in them is more pronounced. On the other hand, the intense pink and the blue diamonds are regarded as highly valuable. Among all colored diamonds, it is the red diamond that is the rarest and the most expensive.

Variety

The color of a diamond is determined by the impurity it holds and is classified under one of two groups. There are a limited number of colors that a diamond can be. These colors include steel gray, white, blue, yellow, orange, red, green, pink, purple, brown and black. The color is due to the presence of impurities or imperfect shape of the stone, but a 'pure' diamond is the epitome of perfection and therefore exceedingly rare.

Colored diamonds are grouped under one of two categories and various sub-categories according to the nature of their impurities and their capacity to absorb light.

The Type-1 diamonds have nitrogen as their main impurity. However, if the N atoms are present in pairs, then they do not bring any change to the color of the diamond; they are called Type IaA. If the N atoms are present in large, even-numbered amounts, then they disperse a yellow color or have a slightly brownish tint; they are grouped under Type IaB. 98% of diamonds belong to Type Ia, which are mostly combinations of IaA and IaB. This type is called Type Ib and it is a very rare occurrence. The synthetic diamonds containing N atoms belong to this group.

The Type 1 diamonds absorb in infrared and ultraviolet rays from 320nm, and feature fluorescence and visible absorption spectrum in them.

The Type 2 diamonds contain very little or no N atoms. Their colors vary from pink to red to brown, which mainly arises from their irregular shapes. These diamonds are rare, but they are extracted in relatively large amounts in Australia. The steely blue or grey ones, which belong to the Type 2b group, have boron as their impurity. These diamonds, representing 0.1% of all gem diamonds, are semiconductors.

Color intensity scale

The color grade as well as the market demands helps determine a diamond's overall value. The Gemological Institute of America has developed a scale ranging from 'D' to 'Z' to determine the 'whiteness' of non-fancy color diamonds. A 'D' stands for colorless and moves down to 'Z' i.e. yellow.

Other diamond grading agencies are the European Gemological Laboratory and American Gemological Society.

Diamonds are graded according market demand and value also. 'High color' diamonds are in much more demand than 'low color' stones.

Value

Colorless to near colorless diamonds are among the most expensive of diamonds, but an unusual and intensely colored diamond can also be extremely valuable. Diamonds' values differ depending on their clarity and colorlessness. In GIA, an 'E' grade diamond is more expensive than a 'Y' grade one because the former is closer to colorless, which is a preferred characteristic in the market. The rarity, limited supply and 'whiteness' are all factors that distinguish a diamond as high grade.