Although diamonds range in every color, a colorless diamond is considered to be more valuable and more sought after than other colors. Colorless diamonds allow light to penetrate the stone, resulting in a rainbow effect. The Gemological Institute of America (GIA) assigns a Color Scale to identify the color of diamonds, and ranges from D (colorless) to Z (brown or light yellow).
The diamond’s color grade is based on its depth of color.
Diamonds that range from colorless (D) to light yellow (Z) or light brown fall into the D-Z grading range.
Where a diamond lands on the color spectrum will affect the price of your diamond and value to consumers. The photograph above displays the level saturation from white to shades of yellow. GIA assigns a letter for the color grade.
White to Yellow-Bodied Diamonds
Most diamonds are white or “yellow-bodied” to a certain degree. D to J colors are considered colorless diamonds but after “D” color, a trained eye can see the yellow color that increases as you fall down the color scale.
“D” color will show no signs of yellow, but a diamond graded “J” and lower start to show noticeable color differences. This is due to the amount of nitrogen in the diamond and the spectrum of light and color released back out of it.
The diamond’s color is most noticeable when the diamond is loose and placed in front of a white background under white light. It becomes even more noticeable when “master diamonds” (pre-color graded diamonds) are used for comparison.
Color grading is not an easy task and a good reason to remove your diamond from its setting so it can be graded loose and/or sent to a diamond grading laboratory for professional diamond grading.
Diamonds set in jewelry cannot be accurately color graded as you cannot view the diamond through the pavilion (bottom of diamond) and compare it to a master set. For this very reason, appraisals are inherently unreliable and inaccurate in the color grades assigned to your diamond.
Overtone and Secondary Colors
On a GIA report, if the diamond has very noticeable brown, the report may state the color such as “K” and then “light brown” or “brown” after it.
In the business brown diamonds are commonly referred to as TLB (Top Light Brown diamonds).
However, when the brown color is very faint, the GIA report does not mention it. Any touch of brown or light greenish color reduces the diamond’s value and is often is a concern of diamond buyers and dealers. Most appraisers miss this or do not mention it in their appraisals. This occurs because they do not notice it or it is hard to see when the diamond is still set in jewelry.
Diamond traders often ask other dealers before they see a diamond if it is Green, Brown or Milky (GBM). This question is even asked when the diamond has a GIA report and is graded “D to J” color.
A trained diamond buyer will also look for any “overtones” or “secondary color”. There are diamonds on the market that have a blend of colors.
For example, it is possible for a 5.0 ct GIA certified diamond as “H” color to have brown overtone or secondary color that GIA does not list or point out on the report. It is not uncommon for an inexperienced individual in the trade or public not to notice this other color and think the “H” color is similar to any other GIA “H” colored graded diamond.
These overtones and secondary color can negatively affect the value and marketability of your diamond. This is another reason why it is best to grade the diamond loose to evaluate the true color of the diamond, whether GIA certified or not.
Fluorescence and Its Affect on Value
Fluorescence in diamonds is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays. On a diamond grading report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight. The light emitted lasts as long as the diamond is exposed to the ultraviolet source. Fluorescence in diamonds is common. Some sources say only 10% of diamonds show strengths of fluorescence that may impact appearance (i.e. the strength of fluorescence is noted on GIA laboratory reports as medium, strong or very strong).
“Blue Fluorescence” is the most common color in diamonds that exhibit fluorescence. In rare instances, the reaction is yellow, white or another color.
In the diamond market, diamonds with the same color grade (H and whiter) with fluorescence often sell for far less than diamonds that do not display fluorescence. Diamonds with H color and above are sold at discounts when they display fluorescence.
Diamonds J and lower color are often thought to benefit from some level of fluorescence. The diamond can appear “whiter” despite the true color and yellow tone that may appear in J color and lower colored diamonds.
Fluorescence, generally, in most every diamond is often considered undesirable and reduces the price of your diamond compared to diamond without any fluorescence.