Pre-Auction Analysis: July 12th, 2023, Sotheby’s Hong Kong

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.

__________________________

Lot: 262

Description: 23.84 ct, Fancy Yellow Diamond, Emerald, VVS2, Rarity, GIA

Analysis:

A large Fancy Yellow Square Emerald diamond with a large face-up dimensions corresponding with a larger carat weight. The inner-grade is strong, bordering to the intense grade. Color dispersion is low with a large colorless areas seen under the table. 

High Auction Estimation: $26,762 pc

Didn’t reach the minimum.

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….9 out of 12

Quality Remark: low color dispersion.

__________________________

Lot: 263

Description: A pair of Fancy Intense Yellow diamonds, BR shaped weighing 8.41 ct and 7.46 ct.

8.41 ct Rarity, GIA
7.46 ct Rarity, GIA

Analysis: 

Two large Round Fancy Intense Yellow diamonds with different dimensions. It seems that in both diamonds the crown was modified to reflect more color under the table area. The Inner-grade is low as well as color dispersion. Rarity Grade is: Rare .

High Auction Estimation: $28.142 pc

Price realized: $26,577 pc

Visual Assets 8.41 ct:

Inner Grade..……………….1

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….6 out of 12

Visual Assets 7.46 ct:

Inner Grade..……………….2

Color Dispersion.………1

Undertone..…………………3

Total Visual Score….6 out of 12

Quality Remark: Open setting.

__________________________

Lot: 285

Description: 6.01 ct, Fancy Yellow Diamond, Cushion, SI2, Rarity, GIA

Analysis: 

A 6-carat Fancy Yellow Cushion-cut diamond with large colorless areas on the face-up view and a low inner-grade. Inclusions (SI2) can be seen with the naked eye through the table. Undertone was impossible to grade due to the fact that the pavilion is completely covered with gold.

High Auction Estimation: $6,794 pc

Price realized: $5,939 pc

Visual Assets:

Inner Grade..……………….1

Color Dispersion.………2

Undertone..…………………N/A

Total Visual Score….N/A out of 12

Quality Remark: SI2 clarity – not eye clean.

__________________________

Lot: 322

Description: 1.37 ct, Fancy Vivid Yellow, Square, VS2, Rarity, GIA

Analysis: 

A Vivid Yellow Radiant cut diamond with a colorless area around the culet and crown. No other undertone appears in the hue exhibiting an absolute yellow. Rarity Grade is: Special.

High Auction Estimation: $26,079 pc

Price realized:$21,314 pc

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….9 out of 12

__________________________

Lot: 329

Description: 2.58 ct, Fancy Intense Purplish Pink, Pear, VS2, Rarity, GIA

Analysis:  

A Fancy Intense Purplish-Pink diamond with a low inner-grade and several colorless patches surrounding the crown. The purple modifier gives the hue a pleasant color sensation. GIA Report is dated 2014, Rarity grade is: Rare .

High Auction Estimation: $311,594 pc

Price realized: $483,541 pc

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

__________________________

Lot: 330

Description: 3.54 ct, Fancy Greenish Blue, Pear, VS2, Rarity, GIA

Analysis:

A 3.54-carat Fancy Greenish Blue Pear-shaped diamond. The inner-grade appears low; however, it is inherent in this color combination. Very few colorless patches are seen through the face-up appearance, and the color sensation meets our expectations based on the color description on the GIA report.

High Auction Estimation: $234,303 pc

Didn’t reach the minimum

Visual Assets:

Inner Grade..……………….3

Color Dispersion.………4

Undertone..…………………4

Total Visual Score….11 out of 12

__________________________

Lot: 346

Description: 3.70 ct, Fancy Intense Green, Cushion, VS2, Rarity, GIA

Analysis: 

A Fancy Intense Green, elongated Cushion shape diamond with a strong inner-grade and high dispersion grade.  No significant undertone is seen in the hue and meets our expectations from the report. The shape depth is 73% .

High Auction Estimation: $379,367 pc

Didn’t reach the minimum

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………4

Undertone..…………………3

Total Visual Score….11 out of 12

Quality Remark: Face-up appears smaller in relation to its weight.

__________________________

 Lot: 348

Description: 21.35 ct, Fancy Vivid Yellow, Radiant, VS2, Rarity, GIA

Analysis: 

A large Vivid Yellow Radiant cut with a step cut facet alignment on the crown and a starburst arrangement on the pavilion. The Inner-Grade is not strong and most of the crown area is colorless. No undertone is visible in the hue.

High Auction Estimation: $71,721 pc

Didn’t reach the minimum

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….9 out of 12

__________________________

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.