Pre-Auction Analysis: March 9, 2022, Sotheby’s New York, Important Jewels

We are happy to bring  you our Sotheby’s Pre-Auction Analysis. We hope it will help those who would like to participate in the auction without physically inspecting the goods.                                                 

Our Sotheby’s New York Pre-Auction Analysis focuses on elements that aren’t visible to the untrained eye. We will describe the important visual elements for those unable to attend the preview and discuss characteristics such as: Undertone, Color Dispersion, and Inner-Grade. These factors, collectively termed UDI, are explained in detail at the end of this article. 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. A grade of “4+” is granted in rare cases and denotes stones with exceptional characteristics. Stones that receive a minimum total UDI score of 8, 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 jewelry brands, collectors, and the investment community.

For your convenience, we have added direct links to the GIA reports.

• All images in this article review were taken with an iPhone 12 Pro; no filters were applied.
• All auction valuations are per-carat and listed in US Dollars

Lot: 221
Description: 1.02 ct, Fancy Vivid Blue, Cushion, VVS2
High Auction Estimation: $980,392 pc
Didn’t reach the minimum
Rarity: A similar diamond enters the market once every… Check Rarity Here
GIA Report: View

Analysis:
An old-mine Vivid Blue Cushion-shape diamond, with Fair symmetry. The low depth percentage makes the diamond appear larger relative to its weight, while an insignificant amount of gray undertone is present in the hue. Most of the diamond color is concentrated in the four corners of the pavilion, leaving many colorless areas on the face-up view. The Vivid Inner-grade is low.
Visual Assets:

Total Visual Score 7 out of 12

Lot: 237
Description: 2.28 ct, Fancy Pinkish-Orange, Pear, IF
High Auction Estimation: $300,000
Price realized: $302,400 total
GIA Report: View

Analysis:
Pinkish-Orange fancy color diamonds are among the rarest color combinations in the category. According to the GIA, the stone is mostly orange with a small amount of pink in the color mix. The inner-grade is high, bordering on intense grade. Although it presents an overall warm color, there is no brown undertone in the diamond’s hue. 

Please note that this stone was offered for sale as lot 1839 at the Sotheby’s HK sale in October 2021.

*Please refer to lot 1839 at the Sotheby’s auction.

Visual Assets:

Total Visual Score 10 out of 12

Lot: 173
Description: 11.02 ct, Fancy Intense Yellow, Modified Pear, VS1
High Auction Estimation: $300,000
Price realized: $390,600 total
Rarity: A similar diamond enters the market once every… Check Rarity Here
GIA Report: View

Analysis:
A large, early century, Fancy Intense Yellow diamond. Examining the unusual shape of the stone, it seems to have been commissioned to be cut and polished to fit the specific design of this Art Nouveau brooch, resulting in a shape between an oval and a pear. The bottom of the stone is polished as a brilliant cut, creating a low color dispersion.
Visual Assets:

Total Visual Score 8 out of 12

Lot: 49
Description: 1.25 ct, Fancy Intense Purplish-Pink, Rectangular, I1
High Auction Estimation: $64,000 pc
Price realized: $60,480 pc
Rarity: An extremely small number of similar diamonds enter the market yearly… Check Rarity Here
GIA Report: View

Analysis:
A Fancy Intense Pink with heavy graining and strong Blue fluorescence, two features that lead to a low translucency and sparkle in this pink diamond. Due to the presence of the purple modifier, the hue is pleasant and the inner-grade is above average. Clarity is I1.
Visual Assets:

Total Visual Score 9 out of 12

Lot: 6
Description: 2.72 ct, Fancy Intense Yellow, old European-cut diamond, VS2
High Auction Estimation: $12,867 pc
Price realized: $23,162 pc
GIA Report: View

Analysis:
A fancy Intense Yellow, old European diamond with fair symmetry and a relatively low depth percentage. A green undertone is present in the color, creating a “cold” hue.
Visual Assets:

Total Visual Score 7 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 a grade of 1, while a stone that exhibits its face-up view with no colorless patches will receive a grade of 4+. Unlike the first two elements, the color dispersion is not a gemological quality and is the result of cutter proficiency.