Magnificent Jewels
Our Christie’s Magnificent 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: 55
Description: 13.71 ct, Fancy Yellow, Round, VVS2, Potentially IF.
Analysis: A large, Fancy Yellow, round brilliant-cut diamond with typical features (large table and low depth, unpolished girdle), indicating it was cut and polished in the mid-last century. The inner-grade appears quite strong when viewed from the side view; however, the face-up view’s impact is minimal due to the unmodified facet alignment. No prominent green or brown undertone is visible in the hue.
High Auction Estimation: $9,803 pc
Realized price: $16,334 pc
Visual Assets:
Inner Grade..……………….4
Color Dispersion.……….1
Undertone..…………………3
Total Visual Score….8 out of 12
Quality Remark: low dispersion
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Lot: 61
Description: 3.19 ct, Fancy Deep Green, Cushion, SI1.
Analysis: A 3.19 carat fancy deep Green cushion-shaped diamond with numerous natural and indented naturals scattered on the surface. The green color is muted which affects the “life” and sparkle of the diamond.
High Auction Estimation: $80,752 pc
Realized price: $122,851 pc
Visual Assets:
Inner Grade..……………….4
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….10 out of 12
Quality Remark: Color is muted
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Lot: 78
Description: 8.77 ct, Fancy Intense Pink, Radiant, VVS1.
Analysis: A large fancy intense pink Radiant cut diamond with a colorless crown and a warm undertone. According to the diamond diary, the face-up of this 8.77 carat appears like a 9.62 – 9.83 carat.
High Auction Estimation: $664,082 pc
Realized price: $588,081 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………2
Total Visual Score….8 out of 12
Quality Remark: Warm undertone. Type IIA
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Lot: 87
Description: 17.61 ct, Fancy Vivid Blue, Pear, IF.
Analysis: A large and rare, vivid blue, pear brilliant-cut diamond. When a fancy color diamond is cut as if it were colorless, it tends to exhibit poor color dispersion, leading to a less striking color experience in the face-up view compared to that of a modified cut. In this case, the color is primarily situated at the point of the shape, leaving the majority of the diamond colorless. The blue hue displays a deep tone, however, without any gray undertone, a combination known to create an “Ink Blue” appearance. The rarity grade assigned to this diamond is “REMARKABLE“—the highest distinction possible for a fancy color diamond.
Realized price: $2,491,900 pc
Visual Assets:
Inner Grade..……………….4
Color Dispersion.………2
Undertone..…………………4
Total Visual Score….10 out of 12
Quality Remark: low color dispersion
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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 is the 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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