Unlike other gem stones, a diamonds quality is judged mostly by the absence of color in them. The worth of diamond jewelry is judged solely by the purity of its brilliance.
Like any other natural stone, however, diamonds come in several shades of colors that are beautiful in themselves.
So far, there is a good range of colors in diamonds, aside from the in-demand blue and pink. Commercially available now are yellow, orange, green, champagne, grey, black, white, red, purple, chameleon and violet diamonds.
Absence of color and perfection
Among jewelers, the finest diamond stones are those that are totally colorless. They are graded D, meaning they are absolutely free of any color.
Theoretically, a chemically pure and structurally perfect diamond is also perfectly transparent with no color whatsoever. However, a good number of all the diamonds used as gems are imperfect.
A tinge of color
The next group are stones with very slight traces of color which can be seen by a diamond expert. When assembled into a finished jewelry, the color shades of these stones usually cannot be discerned anymore. Still, they are graded as E or F color diamonds.
Down the line, those stones which show very little traces of color are categorized as G or H color diamonds, or perhaps I or J color, depending on the strength of the color seen.
Grading and color
Those stones that are graded between D and F are considered colorless. Those that belong in the G to J group are called near-colorless. Those within the K to M grading are slightly colored and the N to Y stones usually looked like light yellow or brown.
One peculiar twist to the rule those diamond stones graded Z are also rare and those bright yellow diamonds are priced higher than the ordinary.
The Gemological Institute of America (GIA) had developed the present color rating system for white diamonds (D down to Z, according to the intensity of the coloration). This has been universally recognized and adapted, overriding the previous older systems.
Fancy
The industry considers diamonds with intense colorations as fancy. An intense yellow coloration is regarded as one of the fancy colors and belongs to a different color grading system.
Gemologists have another rating system for fancy colored diamonds that is different from that used in white diamonds. However, this is not commonly used because these stones are relatively rare.
The color seen in the stones either detract or enhance its value, depending on the color itself and the intensity of the coloration. Examples would include the grade Z bright yellow, or an intense pink or blue in the stones, each one of which commands a better price.
Impurities
There are reasons for these colors in the stones. They could be structural defects in the crystal lattice of the stone or it could be a result of some chemical impurities.
Nitrogen is the most common impurity. It sometimes replaces a small proportion of carbon atoms in the diamond causing a yellowish or brownish tone.
Many impurities and structural flaws produce different colorations in the diamonds. Impurities are almost always present in white diamonds. It is not detectable in the rarest stones.
As always, choosing your diamond jewelry always go back to your own prerogatives on the pros and cons of owning either colored or white diamonds.