Pre-Auction Analysis: Phillips Geneva, May 13th, 2024

Our Phillips The Geneva Jewels Auction: Two Pre-Auction Analysis focuses on elements that are not always visible to the untrained eye. We discuss characteristics such as Inner-Grade, Color Dispersion, and Undertone – collectively termed IDU. Professionals use the IDU method intuitively when analyzing a Fancy Color Diamond. The acronym we use makes these elements easier to remember. 

Members who read this analysis should see it as a valuable supplement to the GIA report. A detailed explanation of the FCRF’s grading methodology can be found at the end of this article. We recommend reviewing it closely to broaden one’s professional vocabulary for describing fancy color diamonds to clients. 

Please note that we analyze and grade diamonds under LED lights and relative to their grade on the GIA report.

The Grades

We use grades 1, 2, 3, and 4, with 1 being the lowest grade. Grade “4+” is granted in rare cases and denotes diamonds with exceptional characteristics. diamonds that receive a minimum total IDU score of 9 without a red remark pass the industry premium threshold and can be traded easily. Fancy Color Diamonds that are graded 10 or above (without a quality remark) are usually sought after by high-end jewelers and collectors.

For your convenience, we have added direct links to diamonds’ GIA reports and FCRF rarity stats.

• All images in this analysis were taken with an iPhone 14 Pro; no filters were applied.
• All auction valuations are per-carat and listed in US Dollars.
• The FCRF evaluates chosen diamonds during each auction based on expert judgments.

Disclaimer

This analysis reflects the opinions of the FCRF professional team. It does not constitute a recommendation to buy or not buy a particular diamond. Buyers assume the responsibility of verifying any information with the auction house. At times, mistakes can happen in the visual analysis and report placement. Therefore, one should not rely solely on this analysis for buying purposes.

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Lot 418

Description: 16.06 ct, Fancy Intense Yellow, Cushion, VS1
High Auction Estimation: $24,907 pc
Price Realised: Didn’t reach the minimum
GIA, Rarity, Diary
True Face-Up: equivalent to that of a 21.675 carat – 35.0% larger than the average

Analysis: A large Fancy Intense Yellow cushion-cut diamond that features a facet arrangement and an open culet, indicating it was polished at the beginning of the last century; however, it seems like the outline was likely modified into a modern cushion shape with pointy corners. The Color Dispersion is very low, leaving room for improvement should professional buyers decide to recut the diamond. According to the FCRF True Face-Up tool, this diamond appears 35% larger in relation to its carat weight, commanding a significant premium.

Visual Assets:
Inner Grade..……………….1
Color Dispersion.………1
Undertone..…………………3
Total Visual Score….5 out of 12
Quality Remark: Low dispersion and Inner Grade.

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Lot 423

Description: 27.27 ct, Fancy Vivid Yellow, Cushion, VS1
High Auction Estimation: $73,341 pc
Price Realised: Didn’t reach the minimum
GIA, Rarity, Diary 
True Face-Up: equivalent to that of a 28.36 carat – 4.0% larger than the average

Analysis: A large Vivid Yellow cushion with minor colorless patches on the crown. The Inner Grade is weak and no significant green or brown Undertone is visible in the hue. 

Visual Assets:
Inner Grade..……………….2
Color Dispersion.………4
Undertone..…………………3
Total Visual Score….9 out of 12

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Lot 425

Description: 2.26 ct, Fancy Intense Green, Radiant, VS1
High Auction Estimation: $168,142 pc
Price Realised: $179,588 pc
GIA, Rarity, Diary
True Face-Up: Moderately below standard.

Analysis: A Fancy Intense Green radiant cut diamond that displays a bright and pleasant color sensation, free of any gray Undertone in the hue. Although the Inner Grade might seem as low, it is considered solid on the green color scale. Two brown patches are located on the girdle opposite each other, with their reflections visible through the table. Those concerned by this reflection should note that these patches confirm the diamond’s natural color.

Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12

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Lot 428

Description: 9.47 ct, Fancy Yellow, Round, VVS2
High Auction Estimation: $12,672 pc
Price Realised: $13,299 pc
GIA, Rarity, Diary 
True Face-Up: Equivalent to that of a 10 carat – 5.6% larger than the average.

Analysis: A mid-century Fancy Yellow round brilliant cut diamond that exhibits a facet alignment indicating the crown was recently polished to enhance the diamond’s color from what was formerly a “cape” diamond. The Inner Grade is weak, and the dispersion is low. Generally, round Fancy Yellow diamonds manipulated to achieve a higher color grade—from a cape diamond to a fancy color—are rarely used in contemporary jewelry as they often fail to meet the color expectations from the GIA report. Most are purchased by diamond dealers who then recut them into radiants or cushions, which are in much higher demand.

Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….7 out of 12
Quality Remark: Low Inner Grade and dispersion

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Lot 429

Description: 1.56 ct, Fancy Red, Round, I2
High Auction Estimation: $961,539 pc
Price Realised: $2,692,008 pc
GIA Rarity Diary
True Face-Up: equivalent to that of a 1.565 carat which is ~0.5% larger than the average

Analysis: The Phoenix, one of the most iconic Argyle diamonds ever offered at their tenders, was sold in the 2013 Argyle Premium Tender to an unknown bidder. Since red diamonds often don’t meet our expectations based on their color descriptions, this diamond is very special as it pushes the visual limits of red color in diamonds.
As seen in the picture taken from the 2013 catalogue, the large and visible inclusions were originally graded by the GIA as I2. However, in rare diamonds like this one, low clarity plays a minor role in determining the price per carat. This red round brilliant cut diamond is a true collectible specimen in the diamond space.

Visual Assets:
Inner Grade..……………….4
Color Dispersion.………4
Undertone..…………………4+
Total Visual Score….12+ out of 12
Quality remark: Not eye clean

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Lot 431

Description: 6.21 ct, Fancy Vivid Pink, Oval, VS1
High Auction Estimation: $2,415,459 pc
Price Realised: $1,929,013 pc
GIA, Rarity, Diary
True Face-Up: is 9.9% larger than the average oval in this weight.

Analysis: Large Vivid Pink diamonds like this one enter the market once a decade and are graded by the Rarity Report as Extremely Rare. The Inner Grade of this Vivid pink is solid, and the colorless crown surrounding the table is quite prominent. No brown Undertone is present in the hue, and the relatively dark tone of pink still provides a pleasant color sensation that meets the expectations for a Vivid pink classification. The light haziness observed in the diamond is a consequence of the type IIa structure in pink diamonds, a feature that might discount the diamond for those seeking a crisp crystal. According to the True Face-Up tool, this oval appears to be a 6.80 ct, presenting a bigger face-up appearance—an important feature that needs to be taken into account when pricing the diamond.

Visual Assets:
Inner Grade..……………….4
Color Dispersion.………4
Undertone..…………………3
Total Visual Score….11 out of 12
Quality Remark: Slightly hazy 

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Discover the IDU Grading Standard

Our pre-auction analysis leverages the IDU Grading Standard to evaluate fancy color diamonds, focusing on three key visual attributes not covered by GIA: Inner-Grade, Undertone, and Color Dispersion. These elements provide deeper insights into a diamond’s color intensity, hue influences, and color evenness—factors critical to its beauty and value. Additionally, our True Face-Up calibration reveals how a diamond’s carat weight translates to its visual presence.

Inner Grade measures the saturation strength within the GIA-defined categories, providing insights into the color’s intensity and richness. From Grade 1, indicating the faintest saturation, to Grade 4+, reserved for the most vivid saturation levels, this grading reveals the depth of a diamond’s color.

Color Dispersion examines how evenly the color is distributed across the diamond’s face-up view. This aspect ranges from Grade 1, showing noticeable colorless areas, to Grade 4+, indicating a flawless color spread.

Undertone evaluates the subtle hue influences within the diamond’s color. The Undertone grade reflects the diamond’s color fidelity and its alignment with the desirable aesthetic standards.

From Grade 1, indicating a significant presence of altering hues that might dilute the primary color’s intensity. to Grade 4+, reserved for diamonds where the Undertone enhances the primary color, making it exceptionally desirable.

Our innovative True Face-Up calibration grade also offers invaluable insights into how a diamond’s carat weight is presented visually, adding another dimension to our comprehensive analysis.

For an in-depth exploration of our grading methodology and how it enhances the valuation of fancy color diamonds, we invite you to read the full article.