Pre-Auction Analysis: Geneva, May 14th 2019, Sotheby’s and May 15th 2019, Christie’s

Our Pre-Auction Analysis focuses on elements that are hidden from the unprofessional eye. As always, we will describe the important visual elements for those who cannot attend the preview. We will 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 description.

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, 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 10, no filters were applied.
• All auction valuations are per carat and in US Dollars.

Sotheby’s, Geneva, Magnificent Jewels and Noble Jewels, May 14th

Lot # 441

20.01 carat Fancy Intense Yellow, radiant cut , VVS1  High catalog estimation: $25,080 pc, GIA # 1192679129

Price Realized: 23,826 pc

A large, Fancy Intense Yellow with a solid Inner-Grade, an average undertone and make with some colorless areas on the face up view 

Total Visual Score: Total Visual Score: 9 out of 12

Lot # 437

1.01 carat Fancy Intense Pink brilliant-cut, High catalog estimation: $99,380pc GIA #8725091

Price Realized: $211,183 pc

Round, brilliant cut, pink diamonds, above one carat, are very rare in the marketplace, especially in the ‘Intense’ category. However, because this size is sought after, whoever polished this pink diamond had to leave a large ‘indented natural’, situated underneath one of the prongs of the ring, to stay above 1ct. The stone has a strong, blue fluorescence as well. The hue has a significant amount of purple and creates a pleasant undertone. The inner grade and color dispersion are above average. The GIA report is dated 1996 and is not available online.

Total Visual Score: 10 out 12 – quality remark

Lot # 435

1.01 carat Fancy Intense Blue Emerald cut VS1 (Tiffany and Co). High catalog estimation: $248,450 pc. GIA # 5192654896

Price Realized: $854,669 pc

An Intense Blue Emerald cut diamond that looks slightly larger than its actual weight due to its low depth (51%). The ring is signed with the Tiffany logo but, buyers should authenticate the ring prior to granting a premium to a branded piece.

The undertone has no grey undertone and exhibits an absolute blue hue, the color dispersion is above average, relative to a step cut diamond and the inner-grade is solid.  

Total Visual Score: 10 out of 12

Lot # 434

7.56 carat Fancy Purplish Pink radiant cut, SI1. High catalog estimation: $238,985 pc.  GIA # 2181113183

Price Realized: Didn’t reach the minimum

A large Fancy Pink Diamond with a ‘cold’ and desirable undertone, a good color dispersion and Inner-Grade, granting a very pleasant overall appearance. The stone has a strong blue fluorescence which may be a caveat for certain buyers and may have an impact on the price.

Total Visual Score: 10 out of 12 – quality remark

Christie’s, Geneva, Magnificent Jewels, May 15th 2019

Lot # 259

71.80 carat Fancy Yellow Oval cut VS1. High catalog estimation: $33,426 per carat. GIA # 6194833450

Price Realized: $22,771 pc

A very large Fancy Yellow oval-shaped diamond, polished as a colorless diamond which results in a very low color dispersion. There is a large ‘feather’, situated 90 degrees to the girdle (as seen in the picture below). This large feather does not appear in its full size on the GIA plot.

Due to the classic cut of this diamond and after examining its body color sideways, we can say that this diamond did not realize the true potential of its color. Re-polishing the diamond could potentially improve the saturation.

 Total Visual Score: 7 out of 12

Lot # 246

2.22 carat Fancy Deep Blue Heart cut VS2

2.00 carat Fancy Deep Blue Heart cut VVS2

High catalog estimation: $1,066,350 pc. 2.22 GIA # 5181910123; 2.00 GIA #1172283975

Price Realized: Didn’t reach the minimum 

Two fancy deep blue heart-shape diamonds, with different visual characteristics.

The 2.22 carat exhibits an absolute Blue color with no gray undertone but due to its poor make and low depth, a large portion of the color doesn’t reflect properly on the face up view and receives a low color dispersion.

The 2.00 carat has some gray undertone in its color mix but has a better color dispersion.

The mounting closes parts of the pavilion and the diamond contour surrounding both heart shapes, gives the feeling to the untrained eye that they are a matching pair.   

2.22

2.00

Total average Visual Score for both stones: 9 out of 12

Lot # 233

118.05 carat Fancy Yellow Cushion cut VS2. High catalog estimation: $29,648 pc. GIA # 2195919509

Price Realized: $59,465 pc

A very rare and large Fancy Yellow ‘Old Mine’ cushion-cut diamond. From the marks on the stone, it is likely to assume that the diamond is a genuine ‘Old-Mine’ and not a contemporary ‘look-a-like’. (Small facets around the open culet were probably added at a later time) The body color is extremely strong and could be improved with a modern facet alignment. The color dispersion is average due to the way the facets are aligned and there is no undertone in the yellow mix.

Total Visual Score:11 out of 12

Lot # 220

0.59 carat Fancy Red Pear cut VS1. High catalog estimation: $847,457 pc. GIA # 13255436

Price Realized: $1,194,007 pc

A Fancy Red Diamond with very good visual characteristics. A slight color difference is seen between the point area and the round part across.  

Total Visual Score: 12 out of 12

Lot # 219

1.40 carat Fancy Vivid Pink Radiant cut, I2. High catalog estimation: $214, 285 pc. GIA # 12790441

Price Realized: $194,622 pc

A Vivid Pink with a very low clarity grade, which may have a serious impact on its price. It exhibits a “cold” and sought-after pink undertone with an average color dispersion.

 Total Visual Score: 10 out of 12 – quality remark

Lot # 218

1.41 carat Fancy Vivid Green-Blue Radiant cut, I2. High catalog estimation: $177, 304 pc. GIA # 15072713

Price Realized: $168,891 pc

A very rare color combination; if it did not have so many negative gemological features it could have been a highly sought-after fancy color diamond. An I2 clarity with indented naturals, ‘Fair’ symmetry and very high depth percentage, making the stone look smaller in comparison to its weight.

Total Visual Score: 11 out of 12 – quality remark

Lot # 217

10.05 carat Fancy Vivid Yellow Radiant cut, VS2. High catalog estimation: $44,776 pc. GIA # 2195402063

Price Realized: $34,825 pc

A relatively large vivid yellow radiant cut with average visual characteristics.

Total Visual Score: 9 out of 12

Lot # 200 A

7.22 carat Fancy Deep Grayish Blue brilliant cut, VS1 type IIb (VAN CLEEF & ARPELS). High catalog estimation: $692,520 pc. GIA # 2191852672

Price Realized: Didn’t reach the minimum 

A grayish-blue diamond with a low amount of ‘gray’ in its color composition and could easily been mistaken as deep blue. The stone has a very poor color dispersion with a colorless center. The Inner-Grade is strong due to its very dark tone. Buyers should authenticate signed pieces especially when stones with gray modifiers appear on jewelry made by ultra high-end brands.      

Total Visual Score: 10 out of 12

General

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