Pre-Auction Analysis: December 11th 2019, Christie’s New York, Magnificent Jewels 

Our Christie’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 # 228

3.07 carat Fancy Vivid Blue, round-cornered rectangular, VVS1. High catalog estimation: $1,302,931 per carat

Market Prevalence: A similar diamond enters the market once every 3-7 years

Price Realized: $1,098,348 pc

An elongated, vivid blue cushion cut with low inner-grade. Very good color dispersion, exhibiting a solid, primary blue hue with no gray undertone. The stone has an extremely thick girdle all around and appears much smaller in relation to its actual weight.   

Total Visual Score:  10+ out of 12

To review the GIA Report Click here

Lot # 395

30.00 carat Fancy Vivid Yellow, Round, VS1. High catalog estimation: $66,666 per carat

Market Prevalence: A similar diamond enters the market once every 25 years

Price Realized: $56,500 pc

A very large, vivid yellow round brilliant with 63% depth. The stone has a low inner-grade and poor color dispersion. The face-up view appears to have more colorless patches than yellow areas

Total Visual Score:  6 out of 12

To review the GIA Report Click here 

Lot # 34

4.20 carat Fancy Vivid Orangy Yellow, Oval, VS2. High catalog estimation: $130,952 per carat

Result: Didn’t reach the minimum

A yellow oval with 15-20% orange modifier in the color mix. The stone exhibits extraordinary features; no brown undertone whatsoever when examining the stone sideways, and the inner-grade is at the highest possible grade. There are two gemological characteristics typically seen in diamonds originating from the Zimmi area in Sierra Leone, a specific black inclusion and fine brown graining lines. Both were detected in the diamond with a  x 10 magnifying loop.

Total Visual Score: 11++  out of 12

To review the GIA Report Click here 

Lot # 223

16.92 carat Fancy Yellow, Radiant, VS1

and

16.36 carat Fancy Yellow, Radiant, VS1

Market Prevalence: 1-2 new similar diamonds enter the market yearly

High catalog estimation: $10,516 per carat

Price Realized: $14,513 pc

A large pair of fancy yellow radiant cut diamonds. Both attain a noticeable green undertone. Inner-grade and dispersion are solid.

To review the GIA Report Click here 

To review the GIA Report Click here 

Total Average Score: 8 out of 12

Lot # 333

18.98 carat Fancy Intense Yellow, old mine brilliant-cut, VS2. High catalog estimation: $18,440 per carat

Market Prevalence: Not applicable for old mine diamonds

Result: Didn’t reach the minimum

A large, old mine cut diamond, with a low inner-grade for an intense diamond and with a low color dispersion, even for an old-mine cut. The “Fair” symmetry grade is quite common for stones polished at the beginning of the last century. The numerous chips on the girdle are evidence of the long period of time this diamond had been worn. A significant recut in this case will be inevitable in order to adjust its proportions to today’s standards.     

Total Visual Score: 6  out of 12

To review the GIA Report Click here

Lot # 144

1.58 carat Fancy Blue, Round, VS2. High catalog estimation: $189,873 per carat

Market Prevalence: A similar diamond enters the market once every 3-7 years

Price Realized: $617,088 pc

Blue fancy color diamonds are rarely seen in the round shape. In most cases it will be evidence for the early period in which they were polished. In this case, the fact that the color wasn’t maximized, the small table and high depth, is evidence  that it was probably cut and polished in the last century. The inner-grade is very high for a fancy blue and there is no gray undertone in the hue, exhibiting an absolute blue. The color dispersion is average.

Total Visual Score:  11 out of 12

To review the GIA Report Click here

Lot # 327

2.53 carat Fancy Purplish Pink, Radiant, VS1. High catalog estimation: $118,577 per carat

Market Prevalence: 4-8 similar stones enter the market per year

Price Realized: $88,932

This 2.53 pink radiant cut appears to miss some of the purple color mentioned in the GIA report and exhibits a “steely” undertone. One of the reasons for that may well be due to the fact that the pavilion is completely covered with white gold. The inner-grade is low and the color dispersion is average

Total Visual Score: 7 out of 12

To review the GIA Report Click here 

Lot # 328

1.07 carat Fancy Intense Blue, Hexagonal step-cut, VVS2. High catalog estimation: $373,831 per carat

Price Realized: $440,186 pc

A novelty shape diamond with high inner-grade and no gray undertone in the blue hue. The color dispersion is very poor and can be seen only at the points of the shape. It is not clear why the GIA graded the distribution “Even” in this case. 

Total Visual Score: 9 out of 12

To review the GIA Report Click here 

Lot # 114

2.09 carat Fancy Intense Pink, Radiant. High catalog estimation: $71,770 per carat

Market Prevalence: 1-3 similar diamonds enter the market yearly

Price Realized: $56,818 pc

A fancy intense pink radiant cut with a “Color only” GIA report. The color dispersion is low with many colorless patches in the crown area. The other two visual elements are average and the inclusion is visible to the naked eye. 

Total Visual Score: 8  out of 12

To review the GIA Report Click here 

Lot # 203

2.50 carat Fancy Deep Brownish Orange, Round, SI2. High catalog estimation: $20,000‬ per carat

Price Realized: $21,000 pc

As opposed to most fancy color diamonds, stones with this unique combination of color and strong saturation are usually polished as a round brilliant cut. They are known in the industry as, “Cognacs” and in most cases have a large cloud situated in the center of the stone, a typical characteristic for stones originating in Namibia.

A 2.50ct is an unusual large size for this type of diamond. It exhibits a very pleasant color overall and the white cloud is not very noticable. 

Our grading system is not applicable in cases of deep and dark saturations. 

Total Visual Score: –  out of –

To review the GIA Report 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.