Pre-Auction Analysis: July 19th, 2022, Sotheby’s Hong Kong – Important Jewels

Our Sotheby’s Hong Kong 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: 217

Description: 1.00 ct, Fancy Intense Pink, Radiant,  I1
High Auction Estimation: $70,066 Total 
Didn’t reach the minimum
Rarity: An extremely small number of similar diamonds enter the market yearly… Check Rarity Here (4-7 yearly)
GIA Report: View

Analysis:
A Fancy Intense Pink Radiant-cut diamond with a pleasant undertone and good color dispersion. The 90% depth makes the stone appear much smaller relative to its weight, and some of the inclusions responsible for the I1 clarity can easily be seen on the table with the naked eye.

Visual Assets:
Inner Grade..……………….2
Color Dispersion.………3
Undertone..…………………3
Total Visual Score….8 out of 12
Quality Remark………….90% Depth and I1 Clarity

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Lot: 218

Description: A pair of 4.00 ct, Fancy Yellow, Pear , VS2
High Auction Estimation: $ 19,108 pc
Price realized: $11,034 pc
Rarity for both: A small number of similar diamonds enter the market yearly… Check Rarity Here (14-18 yearly)
GIA Report A: View
GIA Report B: View 

Analysis:
A matching pair of Fancy Yellow Pear-shaped diamonds with excellent visual assets. The dimensions of each diamond are similar, although their table size and outlines differ. 

The diamonds’ identical weight of 4.00 could be perceived as less attractive in a single stone, as it leaves no slack and implies that the cutter reached the end of his rope (weightwise), although more work could have been done to the stone. However, when a pair of diamonds has a matching weight, it also adds a sense of compatibility to the set, especially at this unusual weight. 

*This pair of earrings was offered in the Hong Kong Sotheby’s sale on April 29th, earlier this year.

Visual Assets:
Inner Grade..……………….4
Color Dispersion.………4
Undertone..…………………4
Total Visual Score…..12 out of 12

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Lot: 263

Description: 3.77 ct, Fancy Vivid Yellow, Radiant, IF
High Auction Estimation: $ 33,791 pc
Price realized: $25,545 pc
Rarity: A small number of similar diamonds enter the market yearly… Check Rarity Here (6-11 yearly)
GIA Report: View

Analysis:
A square Fancy Vivid Yellow Radiant cut with a low Inner-Grade and average undertone in its hue. Dark, colorless areas can be seen in the crown, while the 68% table is rich in color. Based on the diamond’s facet arrangement, depth, and clarity, one can assume that it was once a Round brilliant cut that was repolished into a Radiant to reinforce its color.

Visual Assets:
Inner Grade..……………….2
Color Dispersion.………3
Undertone..…………………3
Total Visual Score…..8 out of 12

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Lot: 265

Description: 1.10 ct, Fancy Purplish- Pink, Oval, SI1
High Auction Estimation: $ 104,227 pc
Didn’t reach the minimum
Rarity: A small number of similar diamonds enter the market yearly… Check Rarity Here (6-12 yearly)
GIA Report: View

Analysis:
A 1.10 carat Fancy Purplish-Pink Oval set in a pink gold cup that covers the entire area from the girdle to the culet. When a Fancy Color Diamond is mounted in a gold cup, it can be challenging to analyze its visual assets, even moreso when a pink diamond is immersed in a pink metal that reflects into the diamond. Thus, we could not reliably analyze the diamond’s inner-grade and undertone. The diamond’s color dispersion is high, covering all areas of the face-up view, and its dimensions appear large relative to its weight.

Visual Assets:
Inner Grade..……………….n/a
Color Dispersion.……….4
Undertone..…………………n/a

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Lot: 294

Description: 1.04 ct, Fancy Pink, Radiant, VS2
Additionally, twelve Pear-shaped Fancy Grey-Violet and Fancy Grey-Blue diamonds totalling 0.92 ct.
High Auction Estimation: $318,473 Total
Didn’t reach the minimum
Rarity: A small number of similar diamonds enters the market yearly… Check Rarity Here (10-13 yearly)
GIA Report: View

Analysis:
A 1.04 carat Fancy Pink Radiant-cut diamond with a solid Inner-Grade and an insignificant undertone. Some black colorless areas can be seen in the crown. The stone’s pavilion is completely covered with pink gold, and as such, we recommend accepting this analysis with some reservation. The face-up view of the diamond is large relative to other stones in its weight category.

Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score…..9 out of 12

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Lot: 312

Description: A pair of 3.01 and 3.00 ct diamonds, Fancy Vivid Yellow, Heart, VS2
High Auction Estimation: $33,913 pc
Didn’t reach the minimum
Rarity for both: A small number of similar diamonds enter the market yearly… Check Rarity for each of the stones, here (6-12 yearly)
GIA Report A: View
GIA Report B: View

Analysis:
Two Vivid Yellow Heart-shaped diamonds with pleasant visual assets. However, when it comes to their outline and table dimensions, we see a significant mismatch that is masked by their gold mounting.

Visual Assets:
3.01 ct
Inner Grade..……………….3
Color Dispersion.………4
Undertone..…………………3
Total Visual Score…..10 out of 12
Quality Remark…………Low compatibility

Visual Assets:
3.00 ct
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score…..9 out of 12
Quality Remark…………Low compatibility

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Lot: 313

Description: 4.05 ct, Fancy Vivid Yellow, Emerald, VS2
High Auction Estimation: $50,326 pc
Didn’t reach the minimum
Rarity: A small number of similar diamonds enter the market yearly… Check Rarity Here (12-14 yearly)
GIA Report: View

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Analysis:
A 4.05 carat Fancy Vivid Yellow Square Emerald-cut diamond with a strong Inner-Grade and almost no yellow or green undertone in its hue. The four corners on the pavilion were not modified in order to concentrate its color, and dispersion is low, resulting in two large, black triangles on the face-up view.

Visual Assets:
Inner Grade..……………….4
Color Dispersion.………2
Undertone..…………………3
Total Visual Score…..9 out of 12

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Lot: 319

Description: A pair of 6.49 and 6.10 ct diamonds, Fancy Intense Yellow, Round, IF
High Auction Estimation: $40,473 pc
Didn’t reach the minimum
Rarity for both: A similar diamond enters the market once every… Check Rarity Here (1-2 years)
GIA Report A: View
GIA Report B: View

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Analysis:
Two Round Brilliant-cut diamonds with similar dimensions, Inner-Grade, and undertone. However, the stones have different table sizes (67% and 63%), leading to low compatibility as a matching pair. The steep angles on the diamonds’ crown and pavilion make it evident that they underwent major recutting to concentrate color under the table and a dark colorless crown at the same time. This visual contrast usually leads to an “Intense” grade at the expense of creating a deformed face up with low color dispersion.

Visual Assets:
Inner Grade..……………….3
Color Dispersion.………2
Undertone..…………………3
Total Visual Score…..8 out of 12
Quality Remark…………Deformed Face Up

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Lot: 327

Description: 1.03 ct, Fancy Pink , Cushion, I1
High Auction Estimation: $127,389 Total for the ring
Price realized: $128,404 Total
Rarity: An extremely small number of similar diamonds enter the market yearly… Check Rarity Here (2-4 yearly)
GIA Report: View

Analysis:
A 1.03 Fancy Pink Radiant-cut diamond with good visual assets with I1 clarity that is visible to the naked eye. The report is dated 2018.

Visual Assets:
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score…..9 out of 12
Quality Remark…………I1 Clarity

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Lot: 328

Description: 1.02 ct, Fancy Intense Purplish-Pink, Pear – color report only
1.01 ct, Fancy Grey-Blue, Pear, VVS1
0.32 ct, Fancy Purplish-Pink, Pear, VS2
0.30 ct, Fancy Blue-Grey, Pear, SI2
High Auction Estimation: $318,473 Total
Price realized: $288,913 Total
GIA Report A: View
GIA Report B: View
GIA Report C: View
GIA Report D: View

Analysis:
A set of four diamonds with four different saturations and color combinations. Placing the four different stones opposite one another may give the illusion of a rare matching set. The 1.02 Fancy Intense Pink Pear Shape has a large visible inclusion on the crown that would probably result in a clarity between I1 and I2 (the GIA report doesn’t include clarity). All other visual assets are specified below.

Visual Assets:
1.02 ct
Inner Grade..……………….3
Color Dispersion.………4
Undertone..…………………4
Total Visual Score…..11 out of 12
Quality Remark…………I1 Clarity

Visual Assets:
1.01 ct
Inner Grade..……………….3
Color Dispersion.………4
Undertone..…………………2
Total Visual Score…..9 out of 12

Visual Assets:
0.32 ct
Inner Grade..……………….4
Color Dispersion.………4
Undertone..…………………4
Total Visual Score…..12 out of 12

Visual Assets:
0.30 ct
Inner Grade..……………….3
Color Dispersion.………3
Undertone..…………………3
Total Visual Score…..9 out of 12
Quality Remark…………SI2

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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.