Magnificent Jewels
Our Christie’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.
__________________________________________________________________________
Lot: 25 A
Description: 2.55 ct, Fancy Intense Blue, Pear, VS2 Rarity, GIA
Analysis:
An old-mine fancy intense blue pear shape with a 57% depth and a 1:1.44 ratio. The low color dispersion is attributed to the periodic facet alignment and the large colorless culet. Buyers who wish to convert the diamond into a modern pear shape with a proper ratio will need to accept a significant loss in weight. The inner-grade is strong, and the presence of gray in the hue is not significant.
High Auction Estimation: $2,500,000 Total
Price realized: $1,804,500 Total
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….8 out of 12
Quality remark: low color dispersion
__________________________________________________________________________
Lot: 43
Description: 2.97 ct, Fancy Vivid Blue, Radiant, VS1 Rarity, GIA
Analysis:
A 2.97ct fancy vivid blue radiant cut diamond with a solid inner-grade and a visible grey undertone in the hue. One of the cut corners (the top right) is larger than the other three, resulting in a lack of symmetry in the outline, which adversely affects the overall aesthetic.
High Auction Estimation: $1,178,451 pc
Price realized: $1,035,354 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………2
Total Visual Score….8 out of 12
__________________________________________________________________________
Lot: 53
Description: A Fancy intense yellow round diamond and two fancy Grayish blue 2.67 ct and 1.52 ct.
Analysis:
A 2.67 round brilliant cut diamond, likely manufactured in the middle of the last century, with a 51% table and a 57% depth. The inner-grade is strong, with a noticeable green undertone. The pair of round grayish blue diamonds exhibit average visual characteristics for this color.
High Auction Estimation: $150,000 Total
Price realized:$151,200 Total
Visual Assets 2.67:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………1
Total Visual Score….6 out of 12
Visual Assets 1.52:
Inner Grade..……………….2
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….7 out of 12
__________________________________________________________________________
Lot: 54
Description: 15.55 ct, Fancy Yellow, Radiant, SI1 Rarity, GIA
Analysis:
A 15.55 ct fancy yellow radiant-cut diamond with a low depth (64.3%) for an elongated rectangular shape. The SI1 clarity grade borders on being one grade lower as it is visible to the naked eye and located just under the table.
High Auction Estimation: $9,646 pc
Price realized: $13,775 pc
Visual Assets:
Inner Grade..……………….4
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….10 out of 12
Quality remark: SI1 visible to the naked eye.
__________________________________________________________________________
Lot: 82
Description: 50.40 ct, Fancy Intense Yellow, Radiant, VVS2 Rarity, GIA
Analysis:
An extremely large Fancy Intense Yellow diamond that combines two different features. Rounded corners, resembling a cushion shape, while the straight outline and step cuts that are inspired by an emerald cut diamond. The depth is 74%, resulting in a smaller face-up appearance relative to the weight.
High Auction Estimation: $23,809 pc
Price realized: $23,500 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
Quality remark: Small face up for its weight
__________________________________________________________________________
Lot: 83
Description: 3.10 ct, Fancy Vivid Blue, Cushion, VS2 Rarity, GIA
Analysis:
A 3.10 carat fancy vivid blue cushion cut, polished as an old-mine. The low color dispersion is typical to an old fashion facet alignment. The inner-grade is solid and no significant gray undertone is visible.
High Auction Estimation: $1,677,419 pc
Price realized:
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….9 out of 12
__________________________________________________________________________
Lot: 88
Description:
A ring with a 4.01 ct Fancy Intense Pink cushion and two Fancy Blue cushion cut weighing 0.55 ct and 0.46 ct Rarity, GIA .
Analysis:
A 4ct fancy intense pink cushion cut with a strong saturation and some colorless patches on the crown. The warm orange undertone is prominent.
According to the Diamond diary, the face-up view corresponds to a ~5.80-carat diamond, which is 47% larger than the average 4-carat fancy color cushion-cut diamond on the market.
High Auction Estimation: $623,441 pc
Price realized: $540,524 pc
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………2
Total Visual Score….8 out of 12
Quality remark: warm undertone
__________________________________________________________________________
Lot: 97
Description: 6.89 ct, Fancy Light Pink, Radiant, VVS1 Rarity, GIA
Analysis:
A 6.89 fancy light pink Radiant cut diamond. Based on the facet alignment and low dispersion, the diamond has been recut from what was previously a round diamond with a lighter saturation. The internal graining has some effect on the translucency of the crystal.
High Auction Estimation: $108,853 pc
Didn’t reach the minimum
Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………3
Total Visual Score….8 out of 12
Quality remark: low dispersion, low translucency
__________________________________________________________________________
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.
You reached your free article limit. Click here to join the FCRF and enjoy all our articles and innovative tools & services.
The article has been sent to your email address. Enjoy!
