Most diamond colors can be artificially induced. Proof that a stone has a natural color can only be obtained from a gemmological laboratory. When considering the purchase of an expensive stone, it is important to have a certificate from an independent laboratory stating the natural origin of its color.  

In reality,  when testing green diamonds, it is difficult to differentiate a natural from an artificially-induced color. The process of artificially altering the color to green involves irradiating which can also occur naturally. Therefore, green stones, despite their rarity, are more difficult to sell unless indisputable proof of colour origin can be found.

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Golden Key will always supply GIA (or similar) certificates for all stones to provide “Peace of Mind” to you, our Client.

The Color Testing / Grading Process

Diamonds are graded for color only as loose, unmounted stones in the inverted position (table down, pavilion up) This process must be conducted under very specific conditions of lighting and background taking into account the distance and angle of the grading inspector in relation to the stone.

A color scale has been devised by the Gem Trade Laboratory of the Gemological Institute of America (GIA). This scale is divided alphabetically from D (the absence of color) to Z (fancy yellow color), and is accepted, recognized and used world-wide. Each letter grade represents a small range of color, and not just a single color. Diamonds are color graded by being compared to a set of master stones. Another important and well-respected grading laboratory is the American Gem Society which uses a similar grading system, but a numerical scale from 0 to 10 (See figure below).

Because both GIA and AGS grading laboratories are known to be hyper-strict and accurate in their color and clarity grading, Golden Key markets and distributes diamonds ONLY with one of these grading reports (certificates, certs) and no others.Colors D, E and F are essentially without color and differ more in transparency. Colors G, H, I and sometimes J, will usually show little or no color in the face-up position (as set in jewelry) for most diamond shapes. However, emerald cut diamonds, which have a large table and large, parallel, step-cut facets will more easily show color from G and above, especially in larger stones. Conversely, sometimes very well cut, round brilliant diamonds of ideal or super-ideal cut quality may show slightly less color than the grade given.

The Effect of Color on the Value of Diamonds
In general, as the amount of yellow in the stone increases, the value of a diamond decreases, that is until the fancy color grades are reached, and then the value goes up again. Roughly, for an internally flawless (IF) round brilliant diamond of 1-1.5ct., prices fall about 25% in going from D to E color, and then about 10% more for each additional grade (F = -35%, G = -45%, H = -55%) until one gets to H color, where the difference decreases to about 5% less going from H to I color (I = -60%). So the first color decrease from D to E will provide you with by far the largest increment in saving money.
Please Note: These numbers are only rough estimates, and are not meant to be used as a pricing guide.

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