Pre-Auction Analysis: October 6th, 2023, Sotheby’s Hong Kong, Magnificent Jewels I

Our Sotheby’s Magnificent Jewels I 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: 1848

Description: 4.01 ct, Fancy Vivid Yellow, Oval modified brilliant-cut, VVS2. Rarity, GIA

Analysis: A 4.01ct vivid yellow oval-cut diamond with exceptional visual assets. The diamond exhibits a rare combination of a high Inner-Grade, high dispersion, and absence of an undertone. Stones that score 12 in the overall grades, whose surface area corresponds to a diamond of a larger carat weight such as this one, are even rarer. . According to the stone’s Diary, its face-up view is 23% larger than that of the average 4-carat fancy color Oval. 

High Auction Estimation: $95,638 pc

Didn’t reach the minimum.

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………4

Undertone..…………………4

Total Visual Score….12 out of 12

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Lot: 1850

Description: 18.08 ct, Fancy Vivid Yellow, Radiant , VVS2. Rarity, GIA

Analysis: A large fancy vivid yellow radiant cut diamond with a noticeable colorless frame around the table. The inner grade is weak and no significant brown or green undertone is visible in the hue. According to the stone’s Diary, the surface outline appears to be in the range of a 18.93 to a 19.32 carat.

High Auction Estimation: $62,226 pc

Price Realized: $55,611 pc

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

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Lot: 1851

Description: 5.01 ct, Fancy Light Pink, Pear-shaped, VS2. Rarity, GIA

Description: 5.63 ct, Fancy Intense Yellow, Pear-shaped, SI1. Rarity, GIA

Analysis: A Toi et Moi ring with two fancy color pear-shape diamonds. The 5.01 carat fancy light pink has a low inner-grade and a pleasant undertone. 

The 5.63 carat has high visual assets however it appears smaller in relation to its weight. According to the stone’s Diary, it appears ~13% smaller relative to its carat weight. The SI1 clarity results from a large group of crystals under the table. 

*A note about the color combination : Using two warm hues next to each other, as opposed to using complimentary colors, might diminish the overall impact of each color in a piece of jewellery. 

High Auction Estimation: $116,127 pc

Didn’t reach the minimum.

Visual Assets (5.01 ct):

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….9 out of 12

Visual Assets (5.63 ct):

Inner Grade..……………….3

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….9 out of 12

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Lot: 1878

Description: 6.02 ct, Fancy Yellow, Radiant, IF. Rarity , GIA

Description: 5.78 ct, Fancy Yellow, Radiant, VS1. Rarity , GIA

Analysis:

Two fancy yellow radiant cut diamonds with similar dimensions. According to the facet alignment, both stones were probably re-cut from larger round brilliant cut diamonds into Radiant cut, to reinforce their saturation. The color dispersion is low as many colorless patches are visible on the face up. 

High Auction Estimation: $16,253 pc

Didn’t reach the minimum.

Visual Assets (6.02 ct):

Inner Grade..……………….2

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….6 out of 12

Quality Remark: low dispersion 

Visual Assets (5.78 ct):

Inner Grade..……………….2

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….7 out of 12

Quality Remark: low dispersion 

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Lot: 1879

Description: 18.08 ct, Fancy Intense Yellow, Oval, VVS1. Rarity, GIA

Analysis: A large intense yellow oval cut diamond. Although the diamond’s pavilion is covered with a yellow gold reflector, the inner-grade appears to be weak and colorless patches are visible through the crown. 

High Auction Estimation: $895,118 (Price includes 3.02 carat Y-Z pear shape)

Didn’t reach the minimum.

Visual Assets:

Inner Grade..……………….1

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….7 out of 12

Quality Remark: low inner-grade 

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Lot: 1887

Description: 22.17 ct, Fancy Vivid Yellow, Square step-cut, VVS2. Rarity, GIA

Analysis: A square Fancy Vivid Yellow emerald-cut diamond displaying a typical cross-shaped pattern of color resulting from the facet alignment. The yellow X shape in the face-up view accentuates the symmetrical colorless areas, which remain distinct even when the stone is tilted, detracting from the overall aesthetic.

High Auction Estimation: $6,921 pc

Didn’t reach the minimum.

Visual Assets: 

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

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Lot: 1892

Description: 74.48 ct, Fancy Vivid Yellow, Cushion modified brilliant-cut, IF. Rarity, GIA

Analysis: A very large fancy vivid yellow cushion shape diamond with a small table (56%) and a very large colorless crown. No green or brown undertone is visible in the hue, exhibiting a pleasant yellow sensation. According to the Diary, the face up appearance is ~7% smaller

High Auction Estimation: $68,670 pc

Price Realized: $33,963 pc

Visual Assets:

Inner Grade..……………….3

Color Dispersion.………2

Undertone..…………………4

Total Visual Score….9 out of 12

Quality Remark: Low dispersion 

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Lot: 1915

Description: 7.09 ct, Fancy Intense Yellow, Radiant, VS1. Rarity , GIA

Description: 7.05 ct, Fancy Intense Yellow, Radiant, VS1. Rarity , GIA

Analysis: Two Fancy Intense Yellow radiant-cut diamonds with similar dimensions. However, their color undertone differs, which might negate the premium typically given to a matched pair.

High Auction Estimation: $74,126 pc

Price Realized: $20,644 pc

Visual Assets (7.09 ct):

Inner Grade..……………….2

Color Dispersion.………2

Undertone..…………………2

Total Visual Score….6 out of 12

Visual Assets (7.05 ct):

Inner Grade..……………….2

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….8 out of 12

Quality Remark: Low compatibility

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Lot: 1916

Description: 12.03 ct, Fancy Intense Yellow, Radiant , VVS1. Rarity , GIA

Analysis: A 12.03-carat Fancy Intense Yellow Radiant-cut diamond with a low inner-grade, bordering on fancy yellow. Much of its face-up view appears colorless, likely because the stone was recut from a round brilliant to reinforce its saturation, aiming for a high yield.

High Auction Estimation: $25,513 pc

Price Realized: $20,221 pc

Visual Assets:

Inner Grade..……………….1

Color Dispersion.………2

Undertone..…………………3

Total Visual Score….6 out of 12

Quality Remark: low inner-grade and dispersion

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Lot: 1920

Description: 6.78 ct, Fancy Yellow, Round brilliant-cut, VVS1. Rarity, GIA

Description: 6.04 ct, Fancy Yellow, Round brilliant-cut, VS1. Rarity, GIA

Analysis: Two fancy yellow Round Brilliant cut diamonds featuring a typical mid-century facet alignment and an open culet. Color dispersion is low and no green or brown undertone are visible in the hue. 

High Auction Estimation: $14,960 pc

Price Realized: $10,743 pc

Visual Assets (6.78 ct):

Inner Grade..……………….2

Color Dispersion.………1

Undertone..…………………4

Total Visual Score….7 out of 12

Quality Remark: Half colored

Visual Assets (6.04 ct):

Inner Grade..……………….1

Color Dispersion.………1

Undertone..…………………3

Total Visual Score….5 out of 12

Quality Remark: Low inner-grade and dispersion 

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Lot: 1921

Description: 30.19 ct, Fancy Yellow, Oval, VS2. Rarity , GIA

Analysis: A large fancy yellow oval cut diamond with noticeable colorless patches on the crown. Inner-grade is high although one needs to be aware the pavilion of the stone is surrounded with a yellow gold reflector. According to the stone’s Diary, the face up of the diamond appears ~7% smaller 

High Auction Estimation: $21,176 pc

Price Realized: $17,190 pc

Visual Assets:

Inner Grade..……………….4

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

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Lot: 1945

Description: 5.17 ct, Fancy Purplish Pink, Pear-shaped, VS2. Rarity , GIA

Analysis: A Fancy Purplish Pink pear-shaped diamond with a low inner-grade and noticeable colorless patches. Its undertone has a pleasant, cool purple hue. The strong blue fluorescence seems to give the stone a slightly hazy appearance.

High Auction Estimation: $247,335 pc

Didn’t reach the minimum.

Visual Assets:

Inner Grade..……………….2

Color Dispersion.………2

Undertone..…………………2

Total Visual Score….6 out of 12

Quality Remark: Strong blue fluorescence- low inner-grade.

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Lot: 1946

Description: 2.65 ct, Fancy Dark Gray-Blue, Radiant, VS1 . Rarity, GIA

Description: 3.88 ct, Fancy Intense Orangy Pink,  Pear modified brilliant-cut, VS1 . Rarity , GIA

Analysis: A 2.65-carat fancy dark gray-blue radiant-cut diamond. The blue body color hue is pronounced and aligns with the color description provided in the report.

A 3.88 carat fancy intense Orangy Pink. Although the diamond’s pavilion is surrounded with a pink gold reflector, the inner-grade appears to be low. The color of the diamond is aligned with the color description. 

High Auction Estimation: $235,011 pc

Didn’t reach the minimum.

Visual Assets (2.65 ct):

Inner Grade..……………….4

Color Dispersion.………3

Undertone..…………………4

Total Visual Score….11 out of 12

Visual Assets (3.88 ct):

Inner Grade..……………….1

Color Dispersion.………3

Undertone..…………………3

Total Visual Score….7 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.