Pre-Auction Analysis: November 27th 2018, Christie’s, Hong Kong, 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. The GIA report of each lot is available for everyone, thus we will discuss the visual characteristics that the report is silent about,  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 distinguishes 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, Hong Kong Magnificent Jewels, November 27th 2018

Lot #2055

2.10 carat Fancy Vivid Blue round, brilliant cut, IF

High catalog estimation: $3,051,786 per carat

The rarity of this Fancy Color Diamond stems first and foremost from its hue, then its saturation and finally, its shape and size. According to the FCRF rarity data, a blue diamond that matches these characteristics is  unearthed once every 10 years approximately. The diamond’s crown is quite steep and lacks color, however it allows to concentrate most of the color in the table area. A side effect of this cut results in a high depth, 64% in this case. The Inner-Grade is very strong, however the blue color has a significant amount of gray.

Total Quality Score: 9

To review the GIA Report Click here (2105997531)

Lot #2054

5.21 carat Fancy Pink Pear, brilliant cut, IF

5.01 carat Fancy Pink Pear, brilliant cut, VS1

High catalog estimation: $438,955 per carat

A matching pair of pink pear shapes, both with extremely thick girdle (both girdles are exceptional in their thickness). The Inner-Grade is low on one of them and average on the other. The pink Undertone is not very “warm” and could meet the expectations of a solid pink. The symmetry is “Fair” on the 5.01ct

5.21 carat:

Total Quality Score: 9

5.01 carat:

Total Quality Score: 8 (Fair symmetry)

To review the GIA ReportClick here (5141763232)

To review the GIA Report Click here (1146987781)

Lot #2053

5.02 carat Fancy Pink Pear, modified brilliant cut, IF

High catalog estimation: $459,591 per carat

Although the stone doesn’t have a purple modifier, it still exhibits a desirable “cold” pink (referred to as “sweet” in professional jargon) . The Inner-Grade is quite low for a Fancy Pink and the Color Dispersion is average. The symmetry is ‘Fair’.

Total Quality Score: 9 (fair symmetry)

To review the GIA Report Click here (2181320831)

Lot #2052

1.63 carat Fancy Vivid Greenish Blue, round brilliant cut, VS2

High catalog estimation: $2,359,049 per carat

The combination of the color and shape characteristics of this 1.63ct, makes it one of a kind. Not only has it got a unique set of gemological features, the three visual elements, (Inner-Grade, Color Dispersion and Undertone) are high.

Total Quality Score: 11

To review the GIA Report Click here (1142097107)

Lot #2051

1.53 carat Fancy Intense Green, cut-cornered rectangular cut, VS1

High catalog estimation: $670,196 per carat

A green diamond with a very strong Inner-Grade and low Color Dispersion, even for an Emerald cut. The green Undertone is quite clear and should correspond well to our expectations of a green diamond as one will imagine it.  

Total Quality Score: 9

To review the GIA Report Click here (1142342054)

Lot #2050

1.92 carat Fancy Vivid Yellowish Orange Pear, modified brilliant cut, VS2

High catalog average estimation: $769,050 per carat.

All three diamonds in this ring exhibit excellent visual parameters, especially on the Inner-Grade of the center stone.

Total Quality Score: 12+

To review the GIA Report Click here (5192301678)

To review the GIA Report Click here (2175151205)
To review the GIA Report Click here (5171101097)

Lot #2049

2.03 carat Fancy Intense Blue Pear, modified brilliant-cut, VVS2

High catalog estimation: $378,842 per carat

Although GIA defines this extremely flat diamond as, a “pear shape” it is actually closer to a ‘Rose-cut’. The advantage of having a diamond with 20% depth is that the surface area is very large, which gives the feeling of a larger diamond in comparison to its weight. The disadvantage on the other hand, is a very poor Color Dispersion. In this case, the blue color appears on the contour of the shape, leaving 90% of the diamond’s face up, completely colorless (nothing like the catalog image).  

 Total Quality Score: 6

To review the GIA Report Click here (2105428211)

Lot #1964

15.10 carat Fancy Yellow Pear, brilliant-cut, IF

14.86 carat Fancy Yellow Pear, brilliant-cut, VS2

High catalog estimation: $27,808 per carat

Two Fancy Yellow Pear-shape diamonds that don’t really match in shape (one resembles to a ‘drop’ and the other to a pear). The facet alignment and Inner-Grade is different as well. In fact, it is safe to say they would probably look better as single stones and less as a pair.   

15.10 carat:

Total Quality Score: 10

14.86 carat:

Total Quality Score: 9 (Low compatibility)

To review the GIA Report Click here (5151211157)

To review the GIA Report Click here (2155192509)

Lot #1962

30.18 carat Fancy Intense Yellow, round-cornered, rectangular modified brilliant-cut, VVS2

High catalog estimation: $40,347 per carat

This 30.18 carat, Fancy Intense Yellow Square Diamond, was a much larger round brilliant cut diamond when it was first transformed from rough to polish.

The reason for re-cutting a yellow round brilliant cut to a square modified diamond (losing approximately 15-20% from its weight) is to lengthen the path of light in the crystal and reinforce its color from a lighter yellow to a much saturated one.

This procedure usually leaves distinct colorless patches in the crown area and table, as seen in this diamond.   

Total Quality Score: 7

To review the GIA Report Click here (10047630)

Lot #1961

24.04 carat Fancy Yellow Pear, modified brilliant-cut, VS2

High catalog estimation: $31,990 per carat

A large looking Fancy Yellow Rose-Cut Diamond, shaped as pear, with very poor Color Dispersion.  

Total Quality Score: 7

To review the GIA Report Click here (5192555037)

Lot #1959

2.04 carat Fancy Intense Purplish Pink, rhomboid step-cut, VS2

High catalog estimation: $534,063 per carat

An odd shaped (Rhomboid) pink step cut diamond with strong Inner-Grade but very low Color Dispersion. The stone has a very low depth percentage and appears much larger in comparison to its weight.    

Total Quality Score: 8

To review the GIA Report Click here (11691578)

Lot #1938

7.48 carat Fancy Vivid Yellow, rectangular-cut, IF

High catalog estimation: $137,086 per carat

A very saturated, vivid, yellow Emerald cut with no green or brown Undertone in the color.

Total Quality Score: 11

To review the GIA Report Click here (5192553159)

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.