Appraising Fancy Color Diamonds

March 31st, 2011 by James L. Sweaney, CGA, FGA. GG
1.97 ct Irradiated Diamond, Fancy Vivid Yellow

1.97 ct Irradiated Diamond, Fancy Vivid Yellow

We just appraised this beautiful bright yellow ~2 ct. round diamond for a client. She had inherited the stone, which was accompanied by an appraisal from a gemologist which described it as a “Canary Yellow” diamond, which implied but didn’t state specifically that the stone was natural-color. Our client said the diamond had originally been purchased at an estate sale for $1200, but this appraisal was for $43,000!

The antennae immediately went up!  First, it’s very unusual to find round natural-color yellow diamonds of this size, especially in today’s market. Diamond cutters have discovered that the Radiant cut maximizes the intensity of color in yellow diamonds, so most of the large natural-color yellow diamonds you see nowadays are radiant cuts.

The clarity of the diamond was at least VS1, perhaps better.

And the color– very intense for a natural-color yellow and thus very rare.

The combination of round shape, high clarity, and bright yellow color meant that if the stone were natural-color,  its appraised value would be well over $70,000! Our advice was to remove the stone from its mounting and send it to GIA for a full grading report to determine origin of color.

As we suspected, the stone proved to be artificially irradiated, with the color grade described as Fancy Vivid Yellow, Artificially Irradiated. Still a very valuable diamond, appraising well over $12,000 for replacement by insurance, but not nearly as rare and exotic as a round VVS2 Fancy Vivid Yellow diamond, natural-color– that would be worthy of an Important Jewels Auction at Christy’s or Sotheby’s!

For an interesting look at some very large and valuable natural-color rough diamonds, including several levels of Fancy Yellow,  follow this link–

Commentary— the use of the term Fancy has evolved over the years. The original designation “Fancy” was used for diamonds of natural color only, which distinguished them from diamonds of treated color.  The level and quality of the color would be described and graded with the terms following “Fancy,” such as Fancy Light Yellow or Fancy Intense Greenish Yellow, etc.

The GIA management and board made a major change in this practice about 10 years ago, after HPHT treated diamonds began showing up in the labs in significant numbers. HPHT means High Pressure High Temperature, a hi-tech treatment developed in the 1990’s that is applied to brownish type 11a diamonds to improve their color grade. Some of these stones were grading near colorless, even colorless, as high as D, while others changed to a range of colors including pink, blue, or yellow! The problem was that some of these HPHT treated diamonds were sold and fully disclosed as being treated, while others were not.

Eventually, the decision was made for the GIA Gem Trade Labs to color grade HPHT treated diamonds (and issue GTL reports with the grading), so long as the girdle of the diamond was laser inscribed HPHT, and further, to grade the color of artificially irradiated diamonds so long as the girdle is laser inscribed “IRRADIATED”– and GIA took it on themselves to laser inscribe any treated stones that came thru their labs.

So now, we have a diamond market in which the color of both natural color and artificially treated diamonds is graded as Fancy. We are not fans of this practice– to us, it dilutes the color grading of the ultra rare natural-color diamonds, and it makes the distinction between natural-color and artificially treated colored diamonds less clear to the consumer.

While GIA is indeed inscribing the girdle of the treated diamonds it sees, the inscription can be can be very hard to see and easily overlooked.  Also, the inscription can be removed by polishing or faceting the girdle of the diamond. We shot this image of the laser inscription on our diamond with a high quality 100mm macro closeup lens– judge for yourself how noticeable the inscription is.

"IRRADIATED" laser inscription
“IRRADIATED” laser inscription

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