Pre-Auction Analysis: November 12th 2019, Christie’s Geneva, Magnificent Jewels

Our Christie’s Geneva 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 # 246

7.03 carat Fancy Deep Blue, Emerald cut. MOUSSAIEFF. High catalogue estimation: $1,991,465 pc

Price realized: $1,666,006

A large fancy deep blue diamond with 69.9% depth and a relatively small table  (51%). Because Deep/Dark Fancy Color Diamonds are highly saturated, analyzing the inner-grade is practically unnecessary as it will always receive the highest possible grade. The undertone on the other hand, plays an important role in Deep blue diamonds. The absence or presence of a gray undertone has a serious visual effect on the esthetic of a deep blue diamond. In this case the amount of gray undertone is quite visible and doesn’t convey a clear sense of a classic deep blue one imagines it to be.  

Prevalence: Enters the market once every 25 years or more 

Total Visual Score: N/A

To review the GIA Report Click here -> 6203146718

Lot # 202 

5.23 carat Fancy Intense Blue, Radiant cut, IF. High catalogue estimation: $860,420 pc

Result: Didn’t reach the minimum

A rectangular blue radiant cut, with a low depth percentage complementing its carat weight. The inner grade is quite low for an intense blue and there are colorless facets in the crown. The undertone is average with a low amount of gray. 

Prevalence: Enters the market once every 8 to 12 years                

Total Visual Score:  8 out of 12

To review the GIA Report Click here -> 2205424972

Lot # 176

32.49 carat Fancy Light Purplish Pink, Radiant cut, VS2. High catalogue estimation: $68,881 pc

Price realized: $78,590 pc

A very large fancy light pink diamond with an extremely low inner-grade. Most of the color is concentrated in the table area, leaving most of the crown with no color. The undertone is average. 

Prevalence: Enters the market once every 8 to 12 years

Total Visual Score:  6 out of 12

To review the GIA Report Click here ->2181741920

Lot # 148

16.21 carat Fancy Deep Yellow, Pear shape, VVS2

and

16.21 carat Fancy Deep Yellow, Pear shape, VS1

High catalog estimation: $10,982 pc

Price realized: $14,627 pc

Looking at the identical gemological characteristics of this large yellow pair, it is safe to say they were cut from the same piece of rough. Their length/width ratio is 1.35, which is not ideal for this shape but the low depth percentage complements their weight and results a pleasant look overall. 

The “strong blue” fluorescence is not visually noticeable. A subtle brown undertone is present in the color and looks nothing like the catalog images. The stones are not modified and are polished as a brilliant cut which creates a large colorless area in the center.    

To review the GIA Report Click here -> 5202462140

To review the GIA Report Click here -> 5201473592

Average Visual Score:  7 out of 12

Lot # 106

16.51 carat Fancy Intense Yellow, Radiant cut, VS1. PEDERZANI. High catalogue estimation: $20,332 pc

Price realized: $18,263 pc

A large fancy intense yellow radiant cut with a high depth percentage of 72%. The stone has a strong Inner-Grade and very few colorless areas. No significant green or brown undertone is present.  

Prevalence: 1-3 similar diamonds enter the market per year

Total Visual Score:  10 out of 12

To review the GIA Report Click here -> 2205532122

Lot # 52

8.96 carat Fancy Intense Yellow, Step cut, VS2. Signed Graff. High catalogue estimation: $22,706 pc

Price realized: $29,455 pc

An Emerald cut diamond with a laser inscription on the girdle mentioning a jewelry brand. The stone has a low inner-grade bordering to a “Fancy Yellow”. Color dispersion and undertone are average. The marks of “time” are evident on the diamond as it is has numerous chips and bruises. 

Prevalence:: 10-12 similar diamonds enter the market per year

Total Visual Score:  7 out of 12

To review the GIA Report Click here -> 13434802

Lot # 87

2.79 carat, Fancy Deep Yellow-Orange, Marquise cut, SI2. BULGARI. High catalogue estimation: $54,691 pc

Result: Didn’t reach the minimum

An orange Marquise with a yellow modifier mounted in a Bulgari signed ring. The diamond has an SI2 due to two large black crystals located on the table and visible to the naked eye (as seen in the picture attached). The four prongs holding the stone seem to be alien to the ring and could have been added at a later time. All of the above makes us rethink whether this Bulgari signed ring was indeed created for this diamond in the first place.   

Total Visual Score:  11 out of 12 – quality remark

To review the GIA Report Click here -> 2247496920

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.