Pre-Auction Analysis: October 7th, 2022, Sotheby’s Hong Kong, Magnificent 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: 1831

Description: 5.02 ct, Pear, Fancy Yellow-Green, SI1

High Auction Estimation: $ 30,454 pc

Price Realized: $24,940 pc

Rarity: Click Here 

GIA Report: View 

Analysis: 

A relatively large green pear-shaped diamond with ~40% yellow color as a modifier in the color mix. The Inner-Grade is very high, though we must consider the fact that the stone’s pavilion and girdle are completely immersed in gold, which may have a positive effect on its Inner-Grade. 

Although the GIA report states there are patches of color in the stone, its color dispersion is perfect and evenly covers the face up view. The Undertone should exceed one’s expectations based on the GIA color description. The SI1 grade is a result of several inclusions on the crown, though they are not visible to the naked eye.

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………4

Undertone..…………………4

Total Visual Score….12 out of 12

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Lot: 1832

Description: 2.20 ct, Round, Fancy Vivid Yellow, SI1 

1.61 ct, Round, Fancy Deep Yellowish Orange, SI2 

High Auction Estimation: $ 229,324 Total

Didn’t reach the minimum

Rarity: Click Here 

GIA Report: View 

GIA Report: View 

Analysis: 

Two non-matching, highly saturated round diamonds with SI1 and SI2 clarity.

The 2.20 carat fancy vivid yellow round brilliant exhibits a solid Inner-Grade for a vivid yellow with no green or brown undertone in the color. The color dispersion is relatively high. The SI1 clarity results from a large inclusion under the table. 

The 1.61 carat fancy deep yellowish-orange has a large cloud in the center of the crystal. This typical inclusion is seen in most deep Fancy Color diamonds, often sourced in Namibia.

Visual Assets: 2.20 ct

Inner Grade..……………….3

Color Dispersion.………3

Undertone..…………………4

Quality Remark: None

Total Visual Score….10 out of 12

Quality Remark:

Visual Assets:

1.61 ct

Inner Grade..……………….4

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

Quality Remark: SI2 clarity.

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Lot: 1833

Description: 8.88 ct, Emerald, Fancy Vivid Orange-Yellow, VS1 

High Auction Estimation: $ 114,776 pc

Price Realized: $122,918 pc

Rarity: Click Here

GIA Report: View

Analysis: 

A fancy Orange Vivid Yellow Emerald cut with a desirable carat weight of 8.88,  a symbol of triple fortune in Asian culture. The stone has a very high Inner-Grade, while its strong yellow fluorescence adds a special glare that enhances the color sensation. 

In a step-cut diamond, colorless areas are usually distributed in a geometric, even manner, making them comfortably integrated in the stone’s geometric pattern. In this case, the large colorless strip in the middle of the stone divides its face up view into two parts, which slightly harms  its overall aesthetic.

Visual Assets:

Inner Grade..……………….4+

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

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Lot: 1835

Description: 3.79 ct, Pear, Fancy Intense Blue, IF

High Auction Estimation: $ 3,822,060 Total

Didn’t reach the minimum

Rarity: Click Here

GIA Report: View 

Analysis: 

A 3.79 carat fancy intense blue pear-shaped diamond with a face up view that corresponds to a much larger carat weight due to its 46.8% depth. The Inner-Grade is very low, bordering on the Fancy Blue grade. Other than some areas on the crown, color is dispersed in most areas of the stone’s face-up view. No gray undertone can be seen in the diamond’s color.  

Visual Assets:

Inner Grade..……………….1

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….8 out of 12

Quality Remark: Low Inner-Grade.

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Lot: 1869

Description: 6.78 ct, Radiant, Fancy Intense Pink, SI2

High Auction Estimation: $ 526,143 pc

Didn’t reach the minimum

Rarity: Click Here

GIA Report: View 

Analysis:

A 6.78 carat radiant cut with a low Inner-Grade and very good color dispersion, leaving two small black areas on the crown. The pink undertone is not  warm and meets our color expectations of a pink diamond. The large feathers on the surface of the crown gives the stone its SI2 clarity grade, and can easily be seen with the naked eye. 

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

Quality remark: Visible SI2.

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Lot: 1883

Description: 6.06 ct, Radiant, Fancy Yellow, VVS2 

6.05 ct, Radiant, Fancy Yellow, VVS2 

High Auction Estimation: $ 15,215 pc

Didn’t reach the minimum

Rarity: Click Here

GIA Report 6213145484: View 

GIA Report 1216161980: View

Analysis:

Two non-matching fancy yellow radiant-cut diamonds mounted in a pair of earrings. Both stones have an old-fashioned facet arrangement, creating a low color dispersion with numerous colorless patches on the crown and in the culet.

Despite efforts to enhance the color of the stones with the closed gold cup covering the pavilion, the Inner-Grade on both stones is still very different, with one bordering on the fancy light grade and the other being a strong fancy yellow.

Visual Assets:

6.06 ct

Inner Grade..……………….3

Color Dispersion.………2

Undertone..…………………4

Total Visual Score….9 out of 12

Visual Assets:

6.05 ct

Inner Grade..……………….1

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….6 out of 12

Quality remark: Non-matching pair, low dispersion.

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Lot: 1884

Description: 13.32 ct, Cushion, Fancy Intense Yellow, VS2, Graff

High Auction Estimation: $ 28,694 pc

Price Realized: $26,512 pc

Rarity: Click Here

GIA Report: View 

Analysis: 

A 13.32 carat fancy intense yellow cushion-cut with a solid Inner-Grade and colorless areas on the crown. No significant  undertone is visible in the diamond’s hue.  

Visual Assets:

Inner Grade..……………….3

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….9 out of 12

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Lot: 1892

Description: 10.26 ct, Oval, Fancy Deep Orangy-Pink, IF

High Auction Estimation: $ 298,016 pc

Withdrawn from auction

Rarity: Click Here

GIA Report: View 

Analysis:

A 10.26 carat fancy deep orangy-pink oval with a face-up surface which corresponds to  a much larger diamond, a result of its 56% depth. The ~15% orange addition is prominent and creates a warm undertone. Overall, the color description should meet our expectations from the GIA color description. Color dispersion is high, regardless of some colorless patches that appear to come and go when tilting the stone.

Visual Assets:

Inner Grade..……………….3

Color Dispersion.………4

Undertone..…………………3

Total Visual Score….10 out of 12

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Lot: 1909

Description: 1.04 ct, Cushion, Fancy Vivid Purplish-Pink

1.01 ct, Cushion, Fancy Dark Bluish-Gray, SI1 

High Auction Estimation: $ 484,128 Total

Didn’t reach the minimum

Rarity: Click Here

GIA Report: View 

GIA Report: View 

Analysis:

A “Toi et moi” ring consisting of a vivid purplish-pink diamond and a fancy gray diamond with a ~15% blue modifier. The 1.04 vivid purplish-pink diamond has a very pleasing cold undertone and a strong Inner-Grade. However, one should bear in mind that it is accompanied by a Color-only report, probably to draw attention away from its low clarity and strong blue fluorescence as seen in the image above. 

The 1.01 fancy bluish-gray diamond corresponds well with the color description on the report, and earns it high marks in all three visual assets.

Visual Assets:

1.04 ct

Inner Grade..……………….4

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

Quality Remark: SI2/I1 clarity and Strong Blue Fluorescence.

Visual Assets:

1.01 ct

Inner Grade..……………….4

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

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Lot: 1911

Description: 3.63 ct, Radiant, Fancy Vivid Purple-Pink

High Auction Estimation: $ 421,163 pc

Withdrawn from auction

Rarity: Click Here

GIA Report: View 

Analysis:

A 3.63 carat fancy vivid purple-pink radiant with a low Inner-Grade and average color dispersion. The cold undertone from the purple addition is pleasing and likely meets one’s expectations of a pink diamond. The GIA report that accompanies the stone is a color-only report, which draws attention away from its low clarity and Strong Blue fluorescence. The stone’s inclusions can be seen with the naked eye. 

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

Quality Remark: Visible low clarity and Strong Blue Fluorescence.

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Lot: 1912

Description: 1.93 ct, Heart, Fancy Vivid Blue 

High Auction Estimation: $ 561,096 pc

Didn’t reach the minimum

Rarity: Click Here

GIA Report: View 

Analysis: 

A 1.93 carat vivid blue heart shape with two large, black inclusions resulting in a clarity grade that is probably SI2 or lower. All of the diamond’s other visual assets are high. 

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………4

Undertone..…………………3

Total Visual Score….11 out of 12

Quality Remark: Low clarity – I1/SI2.

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Lot: 1927

Description: 15.23 ct, Pear, Fancy Vivid Yellow, IF, Bulgari 

High Auction Estimation: $ 54,373 pc

Price Realized: $63,237 pc

Rarity: Click Here

GIA Report: View 

Analysis:

A large vivid yellow pear-shaped diamond with a step-cut facet alignment on the pavilion. Several colorless areas can be seen on the face-up view, including on the culet. The Inner-Grade is solid, and no significant undertone is visible. The surface area of the stone corresponds to a slightly smaller carat weight.

Inner Grade..……………….3

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….9 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.