Color of Diamonds: All Diamonds Have Color
Though a structurally flawless and chemically pure diamond will have no color
and be perfectly transparent, the reality is that nearly all gem-sized diamonds
are flawed in some way and are not one hundred percent transparent. With this
knowledge it’s easy to see why nearly all diamonds are colored diamonds.
Of course there are also diamonds with such intense color that the coloring is
thought to enhance rather than detract from the diamond. Where yellow tinged
diamonds are considered unattractive, such hues as pink or blue are thought to
make a diamond more attractive. The Hope Diamond is probably the most well known
blue colored diamond. Of all colored diamonds, red diamonds are the rarest type
of all.
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Colored diamonds occur in a rather restricted range of color. These include:
white, steel grey, yellow, orange, blue, red, green, purple, pink and even brown
and black. The coloration is caused by structural defects and interstitial
impurities. Light is refracted differently through these flaws and results in
different colored diamonds.
The gemological Institute of America uses a ‘D’ to ‘Z’ scale for grading the
color ‘white’ diamonds, where ‘Z’ is yellow and ‘D’ is colorless. The color
grade scale is as follows:
colorless: D, E, F
near colorless: G, H, I, J
faint yellow or brown: K, L, M
very light yellow or brown: N, O, P, Q, R
light yellow or brown: S, T, U, V, W, X, Y, Z
Many other international diamond grading organizations have also decided to use
the Gemological Institute of America’s color scale for grading diamonds.
So when do diamonds qualify as colored diamonds, per se? When
a diamond is being graded and the color grade is beyond a ‘Z’ rating it is
considered to be a colored diamond. These colored diamonds are then graded by a
different set of guidelines similar to those used for colored gemstones, such as
emeralds, rubies and sapphires.
For the most part, colored diamonds are graded the same as colorless diamonds
with regard to clarity and other features. Interestingly, some diamonds have
enough color to be graded low as a diamond but very high as a general colored
gemstone.
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