Magnificent Jewels
Our Sotheby’s New York 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 stones with exceptional characteristics. Stones 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.
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: 4
Description: 10.27 ct, Fancy Intense Yellow, Radiant, VS1 Rarity , GIA
Analysis:
A 10.27-carat fancy intense yellow Radiant cut diamond. Based on the facet alignment, its low depth, and triangular color areas, we can assume it was repolished from what used to be a round brilliant with a lighter saturation. The inner-grade is strong, and no significant green or brown undertones are visible in the hue. Color dispersion falls within the low range of dispersion grade 3.
High Auction Estimation: $14,605 pc
Price realized: $18,550 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
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Lot: 25
Description: 15.01 ct, Fancy Yellow, Pear, VS1 Rarity , GIA
Analysis:
A large fancy yellow pear shape with a pavilion split into three sections instead of the common four sections. This feature is mostly observed in pear shapes with a low depth percentage in order to yield a larger diamond. A three-section pavilion typically creates a colorless area in the center of the stone, around the culet area, and towards the point. Analyzing the visual assets responsibly was challenging due to the heavy gold plating on the back of the stone.
High Auction Estimation: $ 16,655 pc
Price realized: $16,923 pc
Visual Assets:
Inner Grade..……………….N/A
Color Dispersion.………3
Undertone..…………………N/A
Total Visual Score….N/A out of 12
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Lot: 27
Description: 1.05 ct, Fancy Vivid Blue-Green, Radiant, I1 Rarity, GIA
Analysis:
An unusual and rare vivid green diamond with approximately 60% blue modifier in the hue. All visual assets are high. The clarity is I1 and symmetry is fair. The depth is 80%, which makes this diamond appear smaller in relation to its carat weight.
High Auction Estimation: $ 571,428 pc
Price realized: $459,620 pc
Visual Assets:
Inner Grade..……………….4
Color Dispersion.………4
Undertone..…………………3
Total Visual Score….11 out of 12
Quality Remark: I1, 80% depth, fair symmetry.
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Lot: 28
Description: 19.61 ct, Fancy Yellow, Radiant. VS2 Rarity, GIA
Analysis:
A very shallow fancy yellow radiant-cut diamond. The prominent colorless X pattern under the table is typical for rectangular diamonds with a small crown and low depth percentage (a small crown is created when an octahedron rough diamond is sawn, and the smaller of the two is polished) The color dispersion and inner grade are low.
Additionally, a large natural was left on part of the girdle.
High Auction Estimation: $15,298 pc
Price realized: $13,601 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….7 out of 12
Quality Remark: very low dispersion
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Lot: 30
Description: 5.19 ct, Fancy Green-Yellow, Radiant, SI1 Rarity, GIA
Analysis:
A 5.19 carat yellow diamond with ~40% green hue in the mix. As the diamond’s pavilion is completely covered, we could not analyse the visual properties responsibly.
High Auction Estimation: $120,000 Total
Price realized: $114,300 Total
Visual Assets:
Inner Grade..……………….N/A
Color Dispersion.………N/A
Undertone..…………………N/A
Total Visual Score….N/A
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Lot: 31
Description: 10.26 ct, Fancy Deep Orangy Pink, Oval, IF Rarity, GIA
Analysis:
A large fancy deep pink diamond with approximately 15% orange modifier in the mix. All three visual assets are graded high, and the overall appearance is attractive. According to the Diamond diary, the face-up view of this 10.26-carat diamond appears like a ~14.35 carat diamond. 39% larger than the average fancy color oval of this weight.
High Auction Estimation: $292,397 pc
Didn’t reach the minimum
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
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Lot: 42
Description: 20.80 ct, Fancy Yellow, Cushion, SI2 Rarity, GIA
Analysis:
A large fancy yellow cushion cut and polished with an old-mine facet alignment. The color dispersion is at its lowest, and the inner-grade is low as well. A green undertone is visible in the hue.
Additionally, a large natural was left on the girdle.
High Auction Estimation: $14,423 pc
Price realized: $15,875 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………1
Undertone..…………………2
Total Visual Score….5 out of 12
Quality Remark: Big natural on girdle. Bruises but minor
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Lot: 62
Description: 10.57 ct, Fancy Vivid Purplish Pink, Cushion, IF Rarity, GIA
Analysis:
A 10.57-carat fancy vivid purplish-pink elongated cushion-shaped diamond with an exceptional combination of visual assets. It is a rare occasion for fancy color diamonds, especially at auction, to score as high as 12 with a double +
The saturation is very strong, and the purple modification creates a desirable pink color sensation. Very few colorless patches appear on the crown.
High Auction Estimation: N/A
Price realized: $3,292,763 pc
Visual Assets:
Inner Grade..……………….+4
Color Dispersion.……… 4
Undertone..…………………+4
Total Visual Score….12 out of 12
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Lot: 67
Description: 5.60 ct, Fancy Intense Purplish Pink, Pear, VS2 Rarity, GIA
Analysis:
A 5.60 carat fancy intense purplish pink pear shape with a strong inner-grade and an attractive purple modifier. No other undertone is visible.
High Auction Estimation: $982,142 pc
Didn’t reach the minimum
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………4
Total Visual Score….10 out of 12
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Lot: 87
Description: 10.12 ct, Fancy Intense Yellow, Radiant, VS2 Rarity, GIA
Analysis:
A 10.12 square fancy intense yellow radiant cut with a strong inner-grade and various colorless patches. No undertone is visible in the hue.
High Auction Estimation: $17,786 pc
Price realized: $20,707 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.……3
Undertone..…………………4
Total Visual Score….10 out of 12
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General
We use 1, 2, 3, 4, and 4+ to grade the three visual elements that GIA is silent about, although they impact the value dramatically.
Inner-Grade refers to the strength of color within each GIA saturation category:
Grade 1 weakest, bordering the saturation below.
Grade 2 weak (most common).
Grade 3 full-bodied color (above average).
Grade 4 very strong saturation.
Grade 4+ applies to the vivid category only, exhibiting the strongest possible saturation (rarely seen).
Undertone refers to a subtle hue influence in the body color of the stone.
For example:
A Fancy Blue Diamond with a significant gray presence in its general appearance will be graded with a low undertone grade of 1. A Fancy Blue that has no gray influence that is close to a primary blue will receive the grade, 4.
In a Pink Fancy Color Diamond, a stone with a warm undertone (such as orange or brown) will receive a low undertone grade. A pink stone with a cold undertone (such as purple) will receive a high grade.
In Yellow Fancy Color Diamonds, low foreign influence or a light orange influence will grant the stone a high undertone grade. When the yellow undertone looks like a true primary yellow, it will receive the rare grade 4+. Green and brown undertones will grant a low grade in the yellow category.
Color Dispersion relates to how well the color is dispersed in the face-up view of a Fancy Color Diamond, regardless as to whether the GIA grades the stone as even. A stone with many colorless areas will receive the grade 1, while a stone that exhibits its face-up view with no colorless patches will receive the grade 4+. Unlike the first two elements, the color dispersion is not a gemological quality and is the result of cutter proficiency.
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