How Are Fancy Colored Diamonds Formed & Graded?

Author David Millette
Date Mar 3, 2015

Natural fancy colored diamonds can be found throughout history garnishing the jewelry of royalty. And today, these fancy stones are just as coveted as ever and are high in-demand!

If you have shopped for a diamond before, you know that the price will go up significantly with the presence of more "undesirable" yellow color in the stone. So, what is it that makes "natural fancy" yellow diamonds so special, desired and more expensive?

A diamond's price is determined by how rare the stone is. Diamonds that are graded on the strict GIA color grading scale from D (perfectly colorless) to Z (light yellow), are the most commonly found diamonds in nature. On the other hand, natural fancy colored yellow diamonds have a completely different scale than the less desirable yellow color of most diamonds. These natural fancy colored diamonds form less frequently in nature and are therefore more rare. Not to mention, their color is more vivid and lively than the faint, undesirable color on normal diamonds.

Natural fancy colored diamonds occur when an outside element appears in the formation of a diamond. Let's explore how these coveted diamonds are formed and what makes them so rare:

Yellow, Orange, and Blue Diamonds

Fancy Colored Diamond Fancy Colored DiamondFancy Color Diamond

Without getting too deep into the science behind it, carbon tends to bond with other molecules during the diamond formation process. When this happens, the molecule becomes trapped in the diamond, and it is Incorporated in the overall appearance of the stone.

The most common molecule for the carbon to bond with is nitrogen, which can be found in almost all diamonds. Even colorless diamonds contain some amount of nitrogen, and depending on how it is arranged, this nitrogen can give the diamond a yellow or orange color.

Less common than nitrogen, carbon is also known to bond with boron molecules. This will give the diamond a blue color that gets deeper as the boron present increases.

White and Black Diamonds

Fancy Color Diamond

Having inclusions in a diamond normally detracts from the value. However, it is possible for a diamond to contain so many inclusions that it takes on their color and is deemed a natural fancy color diamond. White diamonds are formed in this manner when sub-microscopic inclusions reduce the diamond's sparkle and make the seemingly colorless diamond turn opaque.

Brown, Pink, Purple, and Red Diamonds

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When a diamond is forming, the carbon molecules bond together in a crystal lattice structure that gives the stone its shape and strength. The same heat and pressure that helped to form the diamond can alter the crystal latice structure of the stone. When this happens, it is possible for it to cause the diamond to absorb certain colors of light and allow others to reflect out. Brown, pink, purple, and red diamonds are all formed from this rare defect.

Green Diamonds

Fancy Color DiamondFancy Color Diamond

Similar to the colors above, green diamonds are formed when the crystal lattice structure of the diamond is altered. What sets green diamonds apart is that their structure isn't altered by heat, but by exposure to naturally occurring radiation during the trip up to earth's surface. These are considered to be the rarest of natural fancy colored diamonds with only a few released to the market each year. In fact, these are so rare that most jewelers have never had a natural green diamond in their stores.

How Are Natural Fancy Colored Diamonds Graded?

Factors, such as clarity and how well the stone reflects light, aren't as important when grading fancy colored diamonds. Since colored diamonds are so rare, the value is based predominantly on the coloration itself. However, this can be difficult because colored diamonds will usually contain multiple colors.

The Gemological Institute of America, or GIA, has two types of reports that you can purchase for a diamond. One being "The GIA Colored Diamond Grading Report", which is very similar to that of a colorless diamond. The second is the "Colored Diamond Identification and Origin" report, which grades color in three different categories: hue, tone, and saturation. The hue is graded on a 27 grade scale, while the tone and saturation are described with terms such as "fancy light" "fancy intense" or "fancy vivid." Unlike colorless diamonds, which are graded on their lack of color, the value of natural fancy color diamonds increases as the colors become more intense.

This report will also inform you of the origin of the stones color, whether it be naturally occurring or altered in a lab. In a process called "diamond enhancement," scientists can replicate the environments that cause the rare irregularities in diamonds. This may give the diamond a fancy color, but it is not as rare or valuable as a real natural fancy color diamond.

Want to see some examples of fancy colored diamonds in person? Long's Jewelers has a wide selection of fancy colored diamonds available at any of our five retail locations. Because these stones are very rare, we want to tailor an experience based on what you are looking for. Make an appointment with one of our Long's diamond experts to see our collection:

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