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.
Lot 495: Fancy Vivid Pink, 15.38 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. It is classified as a Super-stone.
High Estimate, Price Per Carat: $2,450,341; Realized Price (Including Premium): $2,052,093 Price Per Carat (Updated 20/5/16)
This Vivid Pink has quite a low inner-grade (grade 2). The undertone is warm, leaning towards the orange spectrum (grade 2). The color dispersion is very high and earned a grade of 4. The GIA photograph in the Sotheby’s catalogue is the most accurate reference for this stone’s undertone (p 358-359).
Auction houses insist on highlighting a ‘Type IIa’ designation, but the connection between a Type II label and the value of a pink diamond is purely coincidental. Unlike Type II colorless diamonds, Type II pink stones have certain characteristics that are not necessarily positive; in fact, graining and low transparency are common features. In this case, the graining is mentioned on the diamond’s accompanying GIA report. If you place this stone under a white diamond light, it becomes even more orange and loses its sparkle. It also becomes a bit dull, due to the graining.
We encourage members to read our recent article on Type IIa pink diamonds: https://www.fcresearch.org/not-my-type-common-misconceptions-about-type-iia-diamonds/
Lot 494: Fancy Vivid Blue, 7.32 carats; FCRF Rarity Evaluator: Out of all diamonds unearthed, you will only find 1 of 130,000,000 that have similar characteristics. Approximately 1% of Blue stones are graded as Fancy Vivid.
High Estimate, Price Per Carat: $3,385,245
Realized Price (Including Premium): $2,337,790 Price Per Carat (Updated 20/5/16)
The inner grade of this Vivid Blue is very high (grade 4). Its undertone is very good (without a cast of grey) and features a unique tint of ink blue – it receives a high grade of 4. The most noticeable disadvantage is the very low color dispersion (grade 1), which can be attributed to the fact that the stone is very shallow and has a large culet. The stone is more impressive in real life than in the catalogue.
Lot 405: Fancy Intense Blue, 6.64, 2.01 and 1.01 carats
High Estimate, Price Per Carat: $1,436,521
Realized Price (Including Premium): $13,672,493 (Updated 20/5/16)
The undertone of this stone is above average and leans toward a dark tone, receiving an above average grade of 3. The Sotheby’s catalogue portrays the blue marquis with a completely different undertone than it possesses in real life. The color dispersion is a bit above average and receives a 3, but the inner grade is quite high and receives a grade of 4.
Lot 411: Fancy Intense Blue, 6.03 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Only 4% of Blues are between 5 and 9.99 carats.
High Estimate, Price Per Carat: $821,890
Realized Price (Including Premium): $955,253 Price Per Carat (Updated 20/5/16)
As this pear shape is cut as a white stone, the color dispersion is extremely low and receives a grade of 1. The inner grade is below average and receives a grade of 2. Its undertone is above average and receives a grade of 3.
Refer to the photograph on p 262 in the Sotheby’s catalogue for a more accurate image of this stone.
Lot 411A: Fancy Pink, 18.51 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Approximately 15% of Pinks are VVS.
High Estimate, Price Per Carat: $428,395
Realized Price (Including Premium): $528,021 Price Per Carat (Updated 20/5/16)
The GIA report states that this stone has 65% depth; we can mistakenly believe this is a reasonable depth percentage, but for a semi-heart shaped stone it is actually very high. In person, it appears much smaller than an 18 carat diamond.
This stone was re-cut from an old mine style diamond. Its inner grade is above average and receives a 3; color dispersion is low and receives a grade of 2; and the undertone is quite sweet and receives a grade of 3.
Lot 462: Fancy Blue and Fancy Orangey Pink Diamonds, 8.85 carats and 8.79 carats respectively
High Estimate, Price Per Carat: $168,571
Realized Price (Including Premium): $5,989,523 (Updated 20/5/16)
The Fancy Blue diamond resembles its image in the Sotheby’s catalogue on page 304, although the undertone appears slightly different in person. The color dispersion is very low and receives a grade of 2, but the undertone is very high and receives a grade of 4.
This Fancy Orangey Pink diamond appears more orange in person than it does in the Sotheby’s catalogue and receives an undertone grade of 2. For inner grade and color dispersion, it receives an above average grade of 3.
When viewed under a diamond light, its undertone leans toward orange and receives a grade of 1 (most likely, this stone is a Type IIa pink). The color dispersion is above average and receives a grade of 3.
Lot 463: Fancy Pink, 11.19 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Approximately 12% of Pink stones are cut as Pears.
High Estimate, Price Per Carat: $372,309;
Price Realized: Didn’t reach the minimum
Photo not available.
This stone has a very low inner grade of 1 and without the GIA report, one could have easily mistaken it for a Fancy Light Pink.
Lot 472: Fancy Vivid Yellow, 11.88 carats; Rarity: Only 2 to 6 new stones with similar characteristics in the 10+ carat category are added to the market each year. Approximately 6% of Yellows are 10+ carats in weight.
High Estimate, Price Per Carat: $41,717; Realized Price (Including Premium): $99,110 Price Per Carat (Updated 20/5/16)
The inner grade of this stone is quite high and receives a 4. As the stone has a tint in its color, it receives an undertone grade of 2. As seen in the iPhone photograph, the stone does not resemble its image in the catalogue. The color dispersion is quite good for an emerald cut and receives a grade of 3. This stone has an almost 72% depth percentage and appears much smaller than its actual weight.
Lot 480: Fancy Pink, 13.63 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Approximately 23% of Pink diamonds are cut as cushions.
High Estimate, Price Per Carat: $363,609
Price Realized: Didn’t reach the minimum
The image on p 324 is quite close to how the color appears in real life. For its undertone, inner grade and color dispersion, the stone receives a grade of 3.
This stone has a distinct black crystal between the crown and the table, which, surprisingly, was removed from the catalogue image.
Lot 486: Fancy Blue, 14.18 carats; FCRF Rarity Evaluator: A stone with similar characteristics is available in the market only once every few years. Approximately 23% of Blue diamonds are cut as emeralds.
High Estimate, Price Per Carat: $349,506
Realized Price (Including Premium): $260,655 Price Per Carat (Updated 20/5/16)
The image on p 338 is a more accurate representation of how this stone appears in real life. It has a low color dispersion and inner grade and receives a 2. For undertone, it receives an above average grade of 3.
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