Jewels & Jadeite
Pre-Auction Analysis: May 23rd, 2023, Phillips Hong Kong, Jewels & Jadeite
Our Phillip’s Hong Kong Pre-Auction Analysis focuses on elements that are not always visible to the untrained eye. We discuss characteristics such as Inner-Grade, Color Dispersion, and Undertone – collectively termed IDU. Professionals use the IDU method intuitively when analyzing a Fancy Color Diamond. The acronym we use makes these elements easier to remember.
Members who read this analysis should see it as a valuable supplement to the GIA report. A detailed explanation of the FCRF’s grading methodology can be found at the end of this article. We recommend reviewing it closely to broaden one’s professional vocabulary for describing fancy color diamonds to clients.
Please note that we analyze and grade diamonds under LED lights and relative to their grade on the GIA report.
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 premium 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 diamonds’ GIA reports and FCRF rarity stats.
- All images in this analysis were taken with an iPhone 13 Pro; no filters were applied.
- All auction valuations are per-carat and listed in US Dollars.
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.
Description: A pair of earrings with two Fancy Vivid Yellow diamonds of radiant cut weighing 1.69 ct and 1.60 ct.
Two radiant cut diamonds with different dimensions, table percentage and depth. Inner-grade is solid and color dispersion is high. GIA reports are dated 2005.
High Auction Estimation: $61,279 Total
Price realized: $40,164 Total
Total Visual Score….10 out of 12
A round brilliant cut diamond from the mid of the last century with a small open culet and a high crown. The inner-grade is low and color is not dispersed evenly on the face up view.
High Auction Estimation: $82,981 Total
Price realized: $54,066 Total
Total Visual Score….8 out of 12
Quality remark: Low color dispersion
A 2.02 carat oval cut fancy blue diamond with a green modifier. The SI2 clarity is due to a large amount of inclusion under the table. The green fluorescent enhances the green color sensation.
High Auction Estimation: $222,772 pc
Didn’t reach the minimum
Total Visual Score….9 out of 12
Quality remark: SI2 clarity
Description: Two fancy intense yellow radiant cut diamonds weighing 7.05 and 7.28
Two radiant cut diamonds that were recut from round brilliant cut diamonds to enhance their saturation. Large colorless areas are visible on the crown and table, although a broad face-up view is inherent to this re-cut. According to the FCRF Diamond Profiler, these two diamonds appear approximately 24% larger than the average 7-carat fancy color diamond available in the market.
High Auction Estimation: $16,050 pc
Price realized: $17,250 pc.
Total Visual Score….8 out of 12
Quality remark: low dispersion
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.
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 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 is the result of cutter proficiency.