Pre-Auction Analysis: May 11, 2022, Christie’s Geneva – Magnificent Jewels

Our Christie’s Geneva Pre-Auction Analysis focuses on elements that aren’t visible to the untrained eye. We describe important visual elements for those who cannot attend the preview. We discuss characteristics such as: Undertone, Color Dispersion, and Inner-Grade, collectively termed IDU. These visual assets are explained in detail at the end of this article.

It is important to note that we analyze and grade Fancy Color Diamonds relative to their GIA grade.

We use grades 1, 2, 3, and 4, with 1 being the lowest grade. Grade “4+” is granted in rare cases and denotes stones with exceptional characteristics. Stones that receive a minimum total IDU score of 9, without a red remark, pass the industry threshold and can be traded easily. Fancy Color Diamonds that are graded 10 or above (without a quality remark) are usually sought after by high-end jewelers and collectors.

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

• All images in this article review were taken with an iPhone 13 Pro; no modification was applied.
• All auction valuations are per-carat and listed in US Dollars.

Disclaimer
This analysis reflects the opinions of the FCRF professional team. It does not constitute a recommendation to buy or not buy a particular diamond. Buyers assume the responsibility of verifying any information with the auction house. At times, mistakes can happen in the visual analysis and report placement. Therefore, one should not rely solely on this analysis for buying purposes.

Lot: 51
Description: 16.93 ct, Fancy Light Purplish-Pink, Rectangular, VS2
High Auction Estimation: $131,389 pc
Price Realized: $103,373 pc
Rarity: A similar diamond enters the market once every… Check Rarity Here.
GIA Report: View

Analysis:
A large Fancy Light purplish pink radiant cut. The inner-grade is low and large dark colorless patches are seen around the crown. The “cool” purple modifier is not noticable in the color when examining the stone face up, probably due to the orangey-rose gold cup at the bottom of the stone that “warms up” its hue.

Visual Assets:

Lot: 29
Description: 10.28 ct, Fancy Pink-Purple, Marquise, I2
High Auction Estimation: $49,178 pc
Didn’t reach the minimum.
GIA Report: View

Analysis:
A large Purple Marquise diamond with a pink modifier in the color mix. The I2 clarity results from a large number of inclusions spread around the entire face up of stone which are visible to the naked eye.

The color of the stones doesn’t seem to be stable and changes according to the light source to which it is subjected. Under a standard diamond light, the purple body color is seen clearly, but it washes away almost completely when the diamond is viewed under natural light. The picture above was taken next to a window, away from a diamond light. Our grade refers to the stone when exposed to natural light.

Visual Assets:

Total Visual Score: 5 out of 12

Lot: 28
Description: 5.03 ct, Fancy Green, Radiant cut, VS1
High Auction Estimation: $68,346 pc
Price Realized: $65,734 pc
GIA Report: View

Analysis:
A relatively large Fancy Green radiant-cut diamond. Looking at the facet arrangement, the 60% depth, and the large colorless patches around the stone’s crown, it is clear that this diamond was repolished from what used to be a round brilliant, in order to reinforce its color. The table size seems extremely small, which does not correspond to the size that appears on the report (68%). The inner-grade is very low, and a grayish-yellow undertone is present in the hue.

Visual Assets:

Total Visual Score: 5 out of 12

Lot: 27
Description: 2.03 ct, Fancy Intense Blue-Green, Marquise, SI2
High Auction Estimation: $123,511 pc*
Price Realized: 144,084 pc*
*Total price was divided by the center stone only.
GIA Report: View

Analysis:
Looking at this old fashioned radiant-cut diamond, we can assume it was likely manufactured between the 1980s and 1990s. No attempt was made during the manufacturing process to reinforce its color, nor to improve its color dispersion. Examining the diamond with an x10 loop, we can  say that its color results from a green patch of color situated in one of the corners of the diamond.

Visual Assets:

Total Visual Score: 6 out of 12

Lot: 61
Description: 205.07 ct, Fancy Intense Yellow, Cushion, VS2
Price Realized: $69,795 pc
Rarity: Check Rarity Here.
GIA Report: View

Analysis:
While it is clear when this diamond was originally manufactured, the neat facets and extra step around the culet seem to be a more modern addition, implying that it underwent an additional round of polishing in the late 20th century.

The addition of the “step” (as clearly seen on the report) became popular in modern times, as it made it possible to change the angles of the pavilion, while reinforcing its color without disrupting its traditional facet alignment. The inner-grade is very strong, and an insignificant undertone is present in the hue. The low color dispersion is typical of antique diamonds.

Visual Assets:

Total Visual Score: 9 out of 12

General

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

Grade 3 full-bodied color (above average).

Grade 4 very strong saturation.

Grade 4+ applies to 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 that is 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 as to whether the GIA grades the stone as even. A stone with many colorless areas will receive a grade of 1, while a stone that exhibits its face-up view with no colorless patches will receive a grade of 4+. Unlike the first two elements, the color dispersion is not a gemological quality and is the result of cutter proficiency.