Pre-Auction Analysis: December 9th 2020, Sotheby’s New York, Magnificent Jewels

As most of the industry has been prevented from flying during this special period and inspect the lots physically, we believe this current analysis is even more relevant than ever.                                                 

Our Sotheby’s New York Pre-Auction Analysis focuses on elements that are hidden from the unprofessional eye. We will describe the important visual elements for those who cannot attend the preview and discuss characteristics such as: Undertone, Color Dispersion, and Inner-Grade (UDI; a detailed explanation appears at the bottom of this article). When we analyze and grade any Fancy Color Diamond it is always done in relation to its GIA grade.

We use grades 1, 2, 3, and 4, 1 being the lowest grade. Grade + is granted in rare cases and stands for stones with an exceptional characteristic. Stones that receive a minimum total UDI score of 8, without a red remark, are considered to be “Gems” and are generally sought after by high-end jewelry brands, collectors and the investment community.

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

• All images in this article review were taken with an iPhone 11pro, no filters were applied.
• All auction valuations are per carat and in US Dollars.

Lot #30

1.71 carat, Fancy Red, Heart, SI2

Price realized: $1,851,461 pc

High catalog estimation: $2,046,783 per carat

A relatively large Fancy Red diamond with a prominent warm brown undertone. In case the future owner would like to have an updated report, he should pay attention that the report is 8 years old. The shape of this heart shape diamond is somewhat off the grid as seen in the picture on the right and the clarity is SI2.

1.71 ct, F.R, HS, SI2

Total Visual Score 9 out of 12

To review the GIA Report of 1.71 ct F.R Click here 

Lot #75

5.03 carat, Fancy Vivid Pink, Radiant, VS1

High catalog estimation: $2,385,685

Didn’t reach the minimum

Click here to check the rarity of this diamond

Large fancy Vivid Pink diamonds are extremely rare on the market and are highly sought after. According to our rarity data, a similar diamond will enter the market once every 10 years on average. The vivid Inner-Grade, in this case, is very high, and very few colorless patches are seen through the crown. Generally speaking, undertone prefrences are subjective but in this case, we feel that the warm orange undertone hurts the overall esthetic of the stone, and consequently, the demand for this diamond might be lower if the stone had been with a cooler undertone. The GIA report states the Symmetry grade is Fair, an uncommon grade for stones of this caliber. From our analysis, it seems that an attempt to improve the symmetry grade might cause a weight loss that is greater than 4 points. 

According to the millimeter size and other gemological parameters, we found that this stone was auctioned by Christie’s in Geneva in May 2015.  

5.03, F.V.P, Rad, VS1

Total Average Score 10 out of 12

To review the GIA Report of 5.03 ct F.V.P Click here 

Lot #73

3.67 carat, Fancy Intense Blue, Radiant, VS2

High catalog estimation: $953,678 per carat

Price realized: $714,3305 pc

Click here to check the rarity of this diamond

A Fancy Intense Blue diamond with very high visual characteristics.

3.67 ct, F.I.B, Rad, VS2

Total Visual Score 11 out of 12

To review the GIA Report of 3.67 ct F.I.B Click here

Lot #28

2.28 carat, Fancy Vivid Blue, Heart, VVS2

High catalog estimation: $1,425,438 per carat

Didn’t reach the minimum

Click here to check the rarity of this diamond

A Vivid Blue heart shape with a distinct triangle shape. Most heart shaped diamonds that have a 90-degree angle in the pointed area, a very large table (76% in this case) with a combination of a low depth (44%) are usually diamonds that were re-polished from what used to be a triangular cut diamond. Triangle shaped heart shape stones do not correspond to the classic shape and get a discount. All other visual characteristics are quite high. 

2.28 ct, F.V.B, HS, VVS2

Total Visual Score 11 out of 12

To review the GIA Report of 2.28 ct F.V.B Click here 

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Lot #29

2.00 carat, Fancy Vivid Orange, Heart, VS1

Price realized: $947,750 pc

High catalog estimation: $750,000 per carat

Solid Orange Fancy color diamonds are rarer than Fancy Red diamonds. However, they come in much larger sizes and they are more abundant in the “Vivid” grade than in the “Fancy” grade in the orange color category. The strong yellow fluorescence in most cases will grant a very pleasant undertone to Orange diamonds and entails a premium. The millimeter size corresponds to a smaller diamond than a 2 carat.  

2.00 ct, F.V.O, HS, VS1

Total Visual Score 11 out of 12

To review the GIA Report of 1.90 ct F.I.P Click here

Lot #35

1.08 carat, Fancy Vivid Blue, Pear, VVS2

High catalog estimation: $648,148 per carat

Price realized: $858,796 pc

Click here to check the rarity of this diamond

A Vivid Blue pear shape brilliant cut diamond with low color dispersion and a solid blue hue with no gray undertone.  GIA report is dated 2013

1.08 ct, F.V.B, PS, VVS2

Total Visual Score 8 out of 12

To review the GIA Report of 1.08 ct F.V.B Click here 

General

We use 1, 2, 3, 4, and 4+ to grade the three visual elements that GIA is silent about, however 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 abounded).

Grade 3 full-bodied color (above average).

Grade 4 very strong saturation.

Grade 4+ applies for 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 and will be 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 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 has only to do with cutter proficiency.