Pre-Auction Analysis: May 10, 2022, Sotheby’s Geneva – Magnificent Jewels and Noble Jewels

Our Sotheby’s Geneva Pre-Auction Analysis focuses on elements that aren’t visible to the untrained eye. We are describing  important visual elements for those who cannot attend the preview. We discuss characteristics such as: Undertone, Color Dispersion, and Inner-Grade IDU. These visual assets are explained in detail at the bottom of this article.

It is important to note that we analyze and grade Fancy Color Diamonds relative to their GIA grade.

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 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 the GIA reports.

• All images in this article review were taken with an iPhone 13 Pro; no filters were applied.
• All auction valuations are per-carat and listed in US Dollars.

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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 to verify 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: 381
Description: 15.23 ct, Fancy Intense Orangey-Pink, Heart, VVS1
High Auction Estimation: $374,660 pc
Didn’t reach the minimum.
GIA Report: View

Analysis:
A large pink heart-shaped diamond with a ~15% orange modifier. The facet arrangement on the pavilion matches that of a modern modified cut, while the colorless area around the culet indicates it wasn’t polished “by the book,” a possible sign of an earlier production. 

The color of the stone appears differently depending on the light source under which it is placed. Underneath a diamond light, the stone’s hue appears pink, and as it moves further away, the orange modifier becomes more prominent. Nonetheless, it should meet one’s expectations from the report’s color description. The Inner-Grade is average and color dispersion is not high

Visual Assets:

Total Visual Score: 9 out of 12

Lot: 385
Description: 51.15 ct, Fancy Yellow, Old mine brilliant cut, SI1
High Auction Estimation: $14,880 pc
Price Realized: $24,760
GIA Report: View

Analysis:
A very large Fancy Yellow Old-Mine cushion-cut diamond. According to the facet arrangement and the unpolished girdle, it is clear that the stone was cut and polished around the beginning of the last century, if not earlier. The SI1 clarity is a result of several black inclusions at the center of the stone (see second picture). A mild undertone is visible in the stone’s color.

Dispersion is low, as seen in most old-cut diamonds. The Inner-Grade is average. 

Visual Assets:

Total Visual Score: 6 out of 12

Lot: 365
Description: 13.44 ct, Fancy Intense Yellow, Radiant, VS1
High Auction Estimation: $24,325 pc
Price Realized: $30,143 pc
Rarity: An extremely small number of similar diamonds enter the market yearly… Check Rarity Here.
GIA Report: View

Analysis:
A large Fancy Intense Yellow Radiant-cut diamond with an uncommon width-to-length ratio (of 1:1.6) for a radiant. Along the length of the stone, two colorless facets, which are a part of the crown, emphasize its extreme rectangular shape. The diamond’s Inner-Grade is above average.

*Buyers should be aware that the diamond was chipped since its GIA report was issued, several large chips appear on the stone which are not mentioned in the report (see image).

Visual Assets:

Total Visual Score: 9 out of 12

Lot: 359
Description: 3.14 ct, Fancy Intense Blue, Cushion, VS2
High Auction Estimation: $725,587 pc
Didn’t reach the minimum.
Rarity: A similar diamond enters the market once every… Check Rarity Here.
GIA Report: View

Analysis:
A 3.14 carat Fancy Blue cushion-cut diamond. In observing the unique “aqua blue” color of this diamond, one cannot overlook its noticeable soft green undertone. This special color is typical of non-Type IIa blue diamond, most of which originated in the east side of Africa. Buyers accustomed to seeing Blue fancy color diamonds from the Cullinan mine in South Africa, Brazil, or Sierra Leone will find the stone’s color off the grid.

The girdle of the stone is immensely thick (see second image), while its color is dispersed perfectly. The inner-grade is below average for a blue diamond.

Visual Assets:

Total Visual Score: 8 out of 12

Lot: 351
Description: 9.27 ct, Fancy Intense Yellow, Round, I2
High Auction Estimation: $18,736 pc
Price Realized: $20,470 pc
Rarity: A similar diamond enters the market once every… Check Rarity Here.
GIA Report: View

Analysis:
A large, mid-century, round brilliant, set in a yellow gold mounting. The color that reflects from the ring back to the stone prevents us from grading its undertone. The stone has a very large feather crack that penetrates from its girdle towards the table. This typical inclusion occurs during the girdle polishing stage. In fact, the color’s Inner-grade is reinforced by this mirror-like crack, as it bounces light inside the diamond, and because of that, we would rather avoid grading the inner-grade.

Side note:  Common practice in the trade is to re-cut those damaged round diamonds into a heart shape, eliminating the feather by positioning it between the shoulders of the heart shape.

Visual Assets:

Lot: 309
Description: 2.92 ct, Fancy Vivid Yellow, Marquise, SI1 and 3.23 ct, Fancy Vivid Yellow, Marquise, VVS1
High Auction Estimation: $53,160 pc
Price Realized: $41,225 pc
GIA Reports: View and View

Analysis:
Two mid-century, Vivid Yellow Marquise-cut diamonds with a similar face-up appearance. The stones have different facet arrangements on the pavilion, one being modified, which is a sign that the stones were matched in recent years. The color of both stones is situated in their points, leaving a large colorless bowtie in the center of the table. The two stones appear larger relative to their carat weights.

Visual Assets:

Total Average Visual Score: 8 out of 12

Lot: 244
Description: 5.02 ct, Fancy Yellow, Square Emerald Cut, SI1 and 5.11 ct, Fancy Yellow, Square Emerald Cut, SI2
High Auction Estimation: $17,145 pc
Didn’t reach the minimum
Rarity:
Check Rarity Here.
Check Rarity Here.
GIA Reports: View and View

Analysis:
Two Fancy Yellow Emerald-cut diamonds in two different weight categories with different dimensions. The inclusions on both stones are not noticeable. The diamonds’ GIA reports are dated 2017.

Visual Assets:

Total Average Visual Score: 8 out of 12

Lot: 366
Description: 3.08 ct, Fancy Pink, Radiant, VS1
High Auction Estimation: $301,948 pc
Didn’t reach the minimum.
Rarity: An extremely small number of similar diamonds enter the market yearly… Check Rarity Here.
GIA Report: View

Analysis:
A Fancy Pink Radiant-cut diamond with a strong Inner-Grade, a warm undertone, and a high color dispersion.  The stone’s face up view typically corresponds with that of a slightly bigger carat weight.

Visual Assets:

Total Visual Score: 10 out of 12

Lot: 393
Description: 7.17 ct, Fancy Intense Purple-Pink, Rectangular, VVS2
High Auction Estimation: $420,926 pc
Price Realized: $785,996 pc
Rarity: A similar diamond enters the market once every… Check Rarity Here.
GIA Report: View

Analysis:
A Fancy Intense Purplish-Pink diamond with 51% depth. This low depth, combined with an eclectic facet arrangement and open culet, makes the stone appear larger than its actual weight, while resulting in a large, colorless bowtie in the center, typically seen in emerald-cut diamonds.

While the inner-grade is low, the purple modifier creates a pleasant, soft hue sensation. 

Side note: The plot on the GIA report doesn’t correspond to the actual facet arrangement. 

Visual Assets:

Total Visual Score: 8 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.