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A Consumer Guide to Diamonds
Today the 3P’s are as important as the 4C’s.


There are two types of instruments, known as “performance assessment tools,” designed for the measurement and rating of light performance. Your jeweler may use one of each.

The first and most widely accepted type of performance assessment tool was a scanner made by Israel-based Sarin Technologies. The Sarin machine, as it is called, is an indirect assessment device that provides valuable data about a diamond that allows a knowledgeable user to predict from its measurements the diamond’s optical performance.

Sarin uses a photo imaging device to take pictures of a stone at many angles of rotation around its circumference—creating, in effect, a data-profile for it. Each time it photographs the stone, it measures, among other things, crucial angles, girdle thickness, and facet lengths. Once the Sarin data processor finishes scanning the stone, it compiles averages and ranges for each measurement. Both are needed to predict light performance. For instance, the diamond may have an overall pavilion angle of 41 degrees (considered excellent) but it may have a tolerance of 1 or more degrees up and down (considered fair to poor). Just by looking at a Sarin report for that diamond, a jeweler will know whether to consider or reject it for purchase.

Given the Sarin machine’s speed of operation and the detailed data generated, it is easy to see why this instrument is used by every major gem lab around the world, including GIA, AGS, and HRD. In recent years, however, Sarin has met with competition from other scanners made by OGI, also in Israel, and Helium in Russia. (see image 10)




MEASURING Diamonds in Action

Scanner technologies work on inference. If such and such is the case, then you can expect certain results. Jewelers versed in Sarin technology tell us this machine can help them eliminate most diamonds they are offered sight unseen. But there is still a number of diamonds that must be observed to decide whether performance expectations are justified.

Can the differences between such diamonds be measured and translated into performance ratings? Three companies say yes: GemEx, GCAL, and Isee2—all of which use direct assessment technologies to quantify and grade various aspects of light performance.

GemEx makes a machine called the “BrillianceScope,” which records digital images of the diamond under five different angles of illumination. Using special software, a microprocessor analyzes all the white and colored pixels in each image, and compares its pixel tallies to averages arrived at by analyzing large databases of other diamonds. White pixel totals are used to rate brilliance and colored pixel totals are used to rate fire. Scintillation is judged based on the change in pixels from one image to the next. All of these ratings are expressed as markings on bar graphs for each light performance factor. Diamonds are rated “very high,” “high,” “medium,” or “low.” The BrillianceScope can be used to judge all diamond cuts, not just round brilliants.





Diamond ring
Image 1 - Diamond ring from the “Rose” collection by Dalumi.
Ring
Image 2 - Ring featuring a Crisscut center diamond by Christopher Designs.
diamond ring bridal set
Image 3 - Bridal set featuring marquise-like shaped Calla cut diamonds from Nelson Jewellery.
diamond circle necklace
Image 4 - Diamond circle necklace featuring a Lady Heart three-stone diamond pendant from David Arabov & Sons.
diamond engagement ring
Image 5 - Princess cut diamond engagement ring by Amy Levine.
diamond earrings and pendant
Image 6 - Earrings and pendant with Rand ideal cut diamonds from Rand Diamond.
swirl diamond pendants
Image 7 - Stylish swirl diamond pendants from Stuller.
cut diamond
Image 8 - Under very favorable, high contrast white illumination, the ideal cut diamond is capable of emitting fire from every facet of its crown. Photo by Michael Cowing, ACA Gemological Laboratory.
diamond engagement ring and wedding band
Image 9 - Diamond engagement ring and wedding band from Uneek.
diamond engagement rings
Image 10 - Engagement rings featuring invisible set diamond side accents from Jewelex.
diamond brilliance
Image 11 - The Isee2 light measurement system from Overseas Diamonds gives diamond brilliance, fire, and sparkle ratings.
14k white gold engagement ring with baguette diamonds
Image 12 - Semi-mount 14k white gold engagement ring with baguette diamond sides from Dora Wedding Bands & Rings.
rose and white gold diamond ring
Image 13 - Rose and white gold diamond ring by Doron Isaak.
heart shaped diamond pendant
Image 14 - Heart shaped diamond pendant by Uneek.