Important Jewels
Our Sotheby’s’s Important Jewels 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: 63
Description: 3.02 ct, Fancy Intense Yellow, Shield-shaped step-cut, SI1 Clarity. GIA
Analysis: A 3.02 carat fancy intense yellow Shield shaped diamond with a low inner-grade and large colourless areas. Low color dispersion in novelty cut diamonds is quite normal as their shape doesn’t correspond to the ideal facet alignment.
High Auction Estimation: $16,556 pc
Price Realized:$11,775 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….7 out of 12
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Lot: 64
Description: 15.89 ct, Fancy Intense Yellow, Cut-cornered rectangular modified, brilliant-cut, VS1 Clarity. Rarity, GIA
Analysis: A large fancy intense yellow radiant cut diamond exhibits a strong Inner-Grade with no significant green or brown undertone affecting its hue. The elongated portion of the crown is colourless, which enhances its long rectangular shape.
High Auction Estimation: $17,621 pc
Price Realized: $22,379 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
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Lot: 65
Description: 11.28 ct, Fancy Yellow, Cushion-cut, VVS1. Rarity, GIA
Description: 11.22 ct, Fancy Yellow, Cushion-cut, VVS2. Rarity, GIA
Analysis: Two cushion shape diamonds, inscribeed with the GRAFF name, with a different outline and dimensions. The the 11.22 seems to have a colorless frame around the table and a relative streight outline.
High Auction Estimation: $10,232 pc
Price Realized: $13,547 pc
Visual Assets (11.28 ct diamond):
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
Visual Assets (10.22 ct diamond):
Inner Grade..……………….3
Color Dispersion.………4
Undertone..…………………3
Total Visual Score….10 out of 12
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Lot: 67
Description: 10.12 ct, Fancy Light Yellow, Oval-shaped, VS2. Rarity, GIA
Analysis: A 10.12-carat fancy light yellow oval with a GIA report dated 2006 exhibits strong blue fluorescence. However, due to the heavy mounting, it is impossible to analyze the three visual characteristics.
High Auction Estimation: $6,916 pc
Price Realized: $6,903 pc
Visual Assets:
Inner Grade..……………….N/A
Color Dispersion.………N/A
Undertone..…………………N/A
Quality Remark: Strong blue fluorescence.
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Lot: 141
Description: 1.03 ct, Fancy Blue, Pear-shaped, SI2. Rarity, GIA
Analysis: A 1.03 carat fancy blue pear shape with low inner-grade and dispersion. As seen in the picture there are large colorless areas in the rounded area of the shape. A gray undertone is visible in the hue.
High Auction Estimation: $194,174 pc
Price Realized: $160,292 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………2
Total Visual Score….6 out of 12
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Lot: 143
Description: 8.02 ct, Fancy Yellow, Round-cornered rectangular modified brilliant-cut, VS1. Rarity, GIA
Analysis: An 8.02-carat Fancy Yellow cushion shape with a report dated 2009 exhibits prominent colorless areas in the crown, and no substantial green or brown undertone is visible in the hue. The stone’s pavilion is completely covered with yellow gold, preventing us from responsibly analyzing the inner grade.
High Auction Estimation: $8,728 pc
Price Realized: $8,710 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….8 out of 12
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Lot: 144
Description: 4.09 ct, Fancy Intense Yellow, Cushion-cut, VS2. Rarity, GIA
Analysis: A 4.09 fancy intense yellow cushion with a large colorless crown around the table. The inner-grade is strong and no substantial undertone is visible in the hue. Report dated 2015.
High Auction Estimation: $14,669 pc
Price Realized: $12,421 pc
Visual Assets:
Inner Grade..………………3.
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
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Lot: 145
Description: 1.03 ct, Fancy Purplish Pink, Round Brilliant, SI1. Rarity, GIA
Analysis: A relatively large round brilliant fancy purplish-pink cut diamond with an Argyle logo and report number inscribed on the girdle. According to its rarity report, a round diamond with similar gemological characteristics enters the market once every 1-2 years. The inner grade is very weak, bordering on the fancy light grade, and very few flashes of color are seen on the face-up.
High Auction Estimation: $145,631 pc
Price Realized: $160,292 pc
Visual Assets:
Inner Grade..……………….1
Color Dispersion.………1
Undertone..…………………2
Total Visual Score….4 out of 12
Quality Remark: low visual characteristics
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Lot: 159
Description: 18.94 ct, Fancy Intense Yellow, Square emerald-cut, VS1. Rarity, GIA
Analysis: An 18.94-carat Emerald cut diamond with a low inner grade and a visible undertone in the hue. Although large colorless areas are visible on the face-up, this is a common feature with fancy color Emerald cut diamonds. The stone has strong blue fluorescence.
High Auction Estimation: $15,839 pc
Price Realized: $13,411 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………2
Total Visual Score….6 out of 12
Quality Remark: strong blue fluorescence
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Lot: 167
Description: 6.64 ct, Fancy Vivid Yellow, Oval-shaped, VS2. Rarity, GIA
Analysis: A 6.64-carat fancy vivid yellow oval-shaped diamond with a color origin report (dated 2015). The culet of the stone is missing, and the clarity is likely below the SI2 grade.
High Auction Estimation: $27,108 pc
Price Realized: $33,472 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….8 out of 12
Quality Remark: color only report, unpolished culet.
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Lot: 193
Description: 1.01 ct, Fancy Deep Pink, Cushion-cut, SI2. Rarity, GIA
Analysis: A 1.01 fancy deep pink with a brown undertone, SI2 clarity and 73% depth.
High Auction Estimation: $69,306 pc
Price Realized: $62,872 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………1
Total Visual Score….5 out of 12
Quality Remark: low undertone, SI2, small face-up
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Lot: 194
Description: 1.02 ct, Fancy Vivid Orange, Pear-shaped, I1. Rarity, GIA
Analysis: A 1.02-carat fancy vivid orange pear-shaped diamond with a color origin report. Due to the sloppy outline of the diamond, it is reasonable to believe that the diamond was not recently polished. The clarity appears to be lower than SI2 and is visible to the naked eye, with a warm undertone. The diamond is polished like a colorless diamond, resulting in low dispersion.
High Auction Estimation: $78,431 pc
Price Realized: $249,020 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………2
Total Visual Score….7 out of 12
Quality Remark: color only, low clarity, warm undertone.
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Lot: 195
Description: 1.02 ct, Fancy Deep Pink, Emerald-cut, Clarity information is not provided. Rarity, GIA
Analysis: A 1.02 fancy deep pink with a pleasant purple undertone. The diamond has a color origin report probably due to the low clarity, and from the dimensions we have extracted a 76% depth.
High Auction Estimation: $98,039 pc
Price Realized: $186,765 pc
Visual Assets:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….7 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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