May 18th 2016, Christie’s Geneva
Our pre-auction analyses focus on visual elements that are not expressed on the GIA report, such as “inner-grade”, “undertone” and “color dispersion”. We use grades 1, 2, 3, 4 and 4+ to evaluate these features. It is often difficult to identify these characteristics when viewing stones in an auction catalogue. For the first time, we are also including the rarity of each stone, calculated by our Rarity Evaluator tool.
Please note that all photos were taken with an iPhone 6.
In many of the lot descriptions, Christie’s noted that the stones’ weight is ‘approximate’; we questioned why this was specified because with a GIA report, the weight is always stated as an exact measurement.
Lot #242 The Oppenheimer Blue
14.62 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Approximately 23% of Blue stones are cut as Emeralds.
High Estimate, Price Per Carat: $3,170,446
Realized Price (Including Premium): $3,967,351 Price Per Carat (Updated 20/5/16)
It is very rare to see a diamond with a 1:54 ratio and low depth percentage of 59.9% (which is a feature, as low depth makes the diamond appear larger than its actual size). The color is very dark and could easily be mistaken for a Deep Blue. In real life, the stone is nothing like its image in the Christie’s catalogue (Note: Even the iPhone 6 photograph does not capture how dark the stone truly is). There is a large dark area in the center of the stone, which is very typical for an emerald cut fancy color diamond. It has a high inner grade of 4, low undertone grade of 2 and above average color dispersion grade of 3.
Lot 234: Blue and Pink Diamond Earrings, 1.51, 1.65, 3.02 and 3.08 carats
High Estimate, Price Per Carat: $711,908
Realized Price (Including Premium): $5,997,533 (Updated 20/5/16)
In this four-stone ensemble, the Fancy Intense Pink, pear-shaped, 1.65 carat diamond has fair symmetry and strong blue fluorescence. This stone, along with a 3.08 carat Fancy Intense Pink and 3.02 carat Fancy Intense Blue are all brilliant cut, which resulted in very low color dispersion (grade 2). The 3.02 Fancy Intense Blue has an above average inner grade of 3 and low undertone grade of 2 because of its greyish color, which is typical for many blue diamonds.
The 3.08 Fancy Intense Pink has low inner grade of 2, low color dispersion grade of 2 and low undertone that definitely leans toward an orange hue and generates a grade of 2.
There is a significant difference between the way these stones appear in real life and how they are portrayed in the Christie’s catalogue.
After noting the varying report numbers for each stone in this ensemble, we concluded that this piece was created relatively close to the date of the auction. Given that new stones have longer GIA report numbers, it is strange to see shorter report numbers on stones that supposedly entered the market in 2015.
Lot 230: Fancy Bluish Green, 7.58 carats
High Estimate, Price Per Carat: $244,601
Realized Price (Including Premium): $202,620 Price Per Carat (Updated 20/5/16)
Photo not available.
This Fancy Bluish Green stone has a very small table, which creates a significant colorless frame. It appears that this diamond was modified from a different cut, perhaps a round or cushion cut. Evidently, the cutter imposed a modern cut on a shape that was not modern to begin with.
The color dispersion is very low (grade 1) and the GIA supports this by grading its color distribution as ‘Uneven’. Fortunately, this stone has a low depth percentage (60%) and appears larger than its actual size. The inner grade is also very low (grade 1).
Lot 224: Fancy Vivid Orange-Yellow, 12.20 and 11.96 carats
High Estimate, Price Per Carat: $532,927
Realized Price (Including Premium): $11,598,087 (Updated 20/5/16)
These two rare ovals exhibit a unique inner grade (grade 4+), undertone (grade 4) and very high color dispersion (grade 4); to find any matching stones with these three elements in their highest grades is extremely rare.
In the Christie’s catalogue (p 238), we see an excerpt from a GIA monograph discussing the origin of orange diamonds. Though the Kimberly mine is mentioned in the text, due to specific characteristics of the color saturation, the Type Ib report (p 235) and internal graining, we can feasibly assume that these stones hail from the Mano River in the Zimmi area of Sierra Leone.
It is very clear that this unique pair of ovals were manufactured from the same piece of rough and cut by the same cutter, though the facet alignment on each bottom pavilion slightly differs.
This is one of the most exceptional pair of diamonds from the yellow family that has ever been introduced in an auction. Both diamonds are more impressive in real life than in the catalogue.
Lot 83: Fancy Vivid Yellow, 5.18 carats; FCRF Rarity Evaluator: Only 6 to 10 new stones with similar characteristics in the 5 to 10 carat category are coming to the market each year. Approximately 17% of Yellow stones are cut as Rounds.
High Estimate Price Per Carat: $139,194
Price Realized: Didn’t reach the minimum
Photo not available.
In theory, any large, round Vivid Yellow is a very desirable item. After examining the 5.18 up close, we realized that the grades for the three main visual parameters – inner-grade, undertone and color dispersion – are quite low.
The inner-grade is above average (grade 3) and the undertone has a subtle tint, which also earns a low grade (grade 2). The caveat for this stone is the low color dispersion generated by its very shallow crown. Crown angles below the standard (35 degrees) in round fancy color diamonds eliminate significant parts of the color in the face up view.
Lot 196: Fancy Intense Blue Diamonds, 2.50 and 3.02 carats
High Estimate, Price Per Carat: $1,026,310
Realized Price (Including Premium): $4,854,562 (Updated 20/5/16)
The inner grades of these stones are not an exact match: the 2.50 earns a low grade of 2 and the 3.02 earns an above average grade of 3. The undertone of both stones is quite good and receives an above average grade of 3. However, the color dispersion is very low for these stones and receives a grade of 1.
Though there is a half-carat difference between these two stones, they create a matching pair because the 3.02 has a very high depth percentage. One is heavier but smaller and the other is lighter but wider; yet together, they form a matching pair.