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Figure 1 (click to enlarge)


Figure 2 - The 1.93-carat Fancy Vivid blue diamond that was auction by Tzoffey's 1818 during the U.S./International Diamond Week in Israel. (click to enlarge)

  Feeling blue? Well fancy that!

by Menahem Sevdermish FGA D.Litt. and Guy Borenstein, FGA
March 24, 2013


The U.S./ International Diamond Week hosted by the Israel Diamond Exchange, March 17-20, attracted buyers from around the world, who came to shop from Israeli dealers. Gemewizard®, a sponsor of the event, participated and provided demonstrations of its products to interested parties.

The grand finale of the event was a live auction of unique high-quality diamonds and gemstones, conducted by the Israeli-French auction house Tzoffey's 1818. The most important item on the block was a beautiful natural fancy vivid blue heart-shaped diamond (Figure 2), weighing 1.93 carats, accompanied by a GIA certificate. Unsurprisingly, it caught the interest of the Gemewizard team.

This rare blue diamond provides us with an opportunity to share with you how we determine the borders between the fancy grades for blue colored diamonds. For the analysis, we used each of the fancy grade images of the pure blue diamonds in the GemePrice™ system, and imported them into the GemePro™ Sampler. We then analyzed each image to retrieve its tone and saturation levels, and determined its location within tone/saturation matrix of the blue hue.

Looking at the analysis results (Figure 1), we found that practically all images of the various blue grades, including the Light, Fancy Light, Fancy, Fancy Intense, Fancy Vivid and Fancy Deep, show a very light tone grade. Indeed all were located in tone grade 2 (the minimal grade), with the exception of the Fancy Dark grade. This was anticipated, as blue diamonds tend to be light in color.

The various color grades, while sharing the same tone grade of 2, differ in their saturation level. The lighter grades fell below saturation level 1, with the Light blue diamond image showed a saturation level of only 0.5, while the Fancy Light grade displayed slightly higher saturation level of 0.7.

The Fancy blue image was the first grade to pass saturation level 1, and it was followed by a Fancy Intense blue with a saturation level of 2. The Fancy Vivid blue was found to be between saturation level 2 (similar to Fancy Intense) and 3.

For the darker colors, we discovered two interesting results. First, the Fancy Deep Blue was found to possess a tone grade of 2 and saturation level of 4, hinting that it is actually an "over-color version" of Fancy Vivid Blue. Second, the Fancy Dark Blue grade showed a saturation level of 3 and a darker tone grade of 3, placing it in a lower row in the matrix.

There is one thing that we must keep in mind, though. The color analysis was performed using the GemePrice™ blue diamond ruler. In the real world, when it comes to blue, the trade is prepared to give some slack. As mentioned, blue diamonds typically possess lower saturations of body color when compared to other hues, and dealers tend to be more forgiving than they would be were it, for example, a yellow diamond.

Turns out that having the blues isn't all bad.

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