Pre-Auction Analysis: November 13th 2018, Christie’s Geneva, Magnificent Jewels,

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).

We use grades 1, 2, 3, and 4, 1 being the lowest grade. Grade 4+ 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 remark, are considered to be “Gems” and are mostly suitable for 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.

Christie’s, Geneva Magnificent Jewels, November 13th 2018

Lot #311

18.96 carat Fancy Vivid Pink, cut-cornered rectangular cut, VS1

High catalog estimation: $2,657,463 per carat

Realized Price: $2,631,901 per carat

This is a very large, vivid, pink diamond with a low depth percentage, rarely seen in this weight and model. Like many Type IIa pink diamonds, the graining lines create an oily look, to the point where it is visible to the naked eye and harms the translucency. In most cases, graining lines are translated to a VVS clarity. In this case, due to the heavy presence of the graining, it received the VS1 grade. The color dispersion is average, even for a step cut. The Inner-grad is average, as well as the undertone.

Total Quality Score: 9 – heavy graining

(*FCRF image is not availble)

To review the GIA Report Click here (2191528443)

Lot #309

81.40 carat Fancy intense yellow Briolette cut, VS2

High catalog estimation: $30,949 per carat

Realized Price: $35,200 per carat

Although this shape brings an excellent yield from the rough, Fancy color Briolettes are rarely seen in the marketplace. One of the reasons for that is because a Briolette diamond retains color poorly. Due to the fact that light passes uninterruptedly, and with very little reflections within this 360° drop shape, color will be seen mainly on the edges of the diamond. As such, low color dispersion is inherent and should not affect the general grade. If the initial rough would have been polished to a classic pear shape, it’s probable that it would have been a vivid yellow.

Total Quality Score: 8

To review the GIA Report Click here (5151849719)

Lot #306

8.25 carat Fancy Deep, Orangy-Pink, cut-cornered rectangular mixed cut, VVS1

High catalog estimation: $427,513 per carat

Realized Price: $448,166 per carat

A relatively rare combination between the ‘Deep’ saturation and the color mix, especially in this carat size. The graining in the stone is quite visible but doesn’t effect the translucency of the crystal. A warm undertone “comes with the territory” when ‘Orange’ is a modifier but overall, it doesn’t have a strong brown look most of these diamonds have; color dispersion is high.

Total Quality Score: 11

To review the GIA Report Click here (5171375961)

Lot #293

7.58 carat Fancy Bluish-Green, round-cornered square cut, VS1

High catalog estimation: $199,415 per carat

Not Sold – Didn’t reach the minimum

This 7.58ct was modified from what used to be an old mine cut diamond, polished at the beginning of the previous century. The modified fact alignment is quite obvious and the uneven color distribution supports that notion. The strong, blue fluorescence has a little impact on the overall esthetic.

Total Quality Score: 7

To review the GIA Report Click here (2165546962)

Lot #287

8.85 A Fancy Blue pear, modified brilliant-cut, VS2

8.79 carat Fancy Orangy-Pink pear, modified brilliant cut, VVS2

High catalog estimation: $342,759 per carat

Realized Price: $263,511 per carat

8.85 – A Fancy Blue Pear Shape with almost no gray undertone and a low color dispersion.

Total Quality Score: 7

8.79 – A Fancy Orangy-Pink with a very warm undertone and average color dispersion.

Total Quality Score: 7

To review the GIA Report Click here (13688407)

To review the GIA Report Click here (12996469)

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 Bue 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.