Pre-Auction Analysis: Phillips New York, June 12th, 2024

Our Phillips The New York Jewels Auction 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 13 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 108

Description: 4.43 ct, Fancy Vivid Yellow, Oval, SI2
High Auction Estimation: $33,861 pc
Price Realized: $24,368 pc
GIA Rarity Diary
True Face-Up: Translates to the visual appearance of a 5 ct = 12.9% larger

Analysis: A 4 ct Vivid Yellow oval-cut diamond that exhibits prominent colorless patches on the crown and features a warm Undertone.

Quality Remark: Warm Undertone, SI2

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Lot 112

Description: 4.01 ct, Fancy Intense Green, Cushion
High Auction Estimation: $87,282 pc
This lot was withdrawn from auction
GIA Diary
True Face-Up: Translates to the visual appearance of a 5 ct = 24.7% larger

Analysis: Fancy intense Green diamonds of this size are rarely seen; however, it is important to note that this diamond comes with an identification and origin report (commonly referred to as a ‘half report’), likely issued to avoid highlighting its various flaws, such as its very low clarity grade, probably an I2 in this case. 

Quality Remark: Half report, low clarity, significant natural

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Lot 125

Description: 45.07 ct, Fancy Vivid Yellow, Emerald, VS1
High Auction Estimation: $77,657 pc
This lot was withdrawn from auction
GIA Rarity Diary
True Face-Up: Moderately below standard

Analysis: A very large Vivid Yellow emerald-cut diamond that features a solid Inner-Grade and very high Color Dispersion for a step cut. Despite its depth percentage of 68% and excellent polish and symmetry grades, its visual presence translates to a diamond appearing smaller in carat weight. This serves as a reminder that depth percentages in fancy color diamonds should not be used as an indication to match the carat weight with its actual face-up size.

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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, determining the level of saturation. 

Grade 1 places the saturation in doubt, indicating it borders on the saturation below. 

Grade 2 is a weak saturation, 

Grade 3 refers to a solid saturation, 

Grade 4 borders on one saturation above. In the vivid category, 

Grade 4+ is reserved for exceptional saturation.

Color Dispersion examines literally how well the color mosaic is dispersed across the diamond’s face-up view. 

This aspect ranges from Grade 1, showing noticeable colorless areas, to Grade 4+, indicating perfect dispersion.

Undertone evaluates the subtle color influences within the diamond’s color, such as brightness or muted tones. 

The undertone grade reflects the diamond’s color sensation and how well it meets our expectations of the color. 

Grade 1 indicates a significant presence of another color. 

Grade 2 indicates a mild foreign sensation. 

Grade 3 indicates an insignificant undertone (most abundant). 

Grade 4 is the pure form of the color.

Grade 4+ is reserved for pink diamonds where the undertone enhances the primary color, making it exceptionally desirable.

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.