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

GCAL (Gem Certification & Assurance Lab), which uses a modified version of a spectrophotometer developed for light measurement in 1996, offers brilliance ratings as well as ratings for optical symmetry. GCAL feels there is a high correlation between these two factors.

Isee2 is the name given to a light measurement instrument developed by a Belgian diamond company to help demonstrate the superiority of its own brand of high-performance stones. Isee2 gives brilliance, fire, and sparkle ratings. The Isee2 machine analyzes the performance with a multitude of digital images taken as the diamond is rotated in a special lighting. One distinctive feature of the Isee2 system is that it displays a video of the diamond performing during the analysis. These images can be reproduced on diamond reports and viewed live by consumers to help them decide which diamond to purchase. (see image 11)


In 1996, the American Gem Society (AGS), a retailer group started by Robert Shipley in 1934, three years after he founded the Gemological Institute of America (GIA), introduced what has proven the most important innovation in diamond grading since its beginning in 1952: cut grades for round brilliant diamonds. AGS was the right group to take this step.

From its earliest days, the society had advocated finely-made diamonds, especially what are known as “ideal cuts.” In the 1940s, it began a project to codify cutting standards and develop diamond ratings for perfection of make (a diamond trade term for the overall quality of a diamond’s cutting). Perfection for AGS meant adherence to proportions recommended by Belgian cutter Marcel Tolkowsky in his 1919 treatise, “Diamond Design.” If cut to Tolkowsky’s preferred angles, stones received a “zero” (on a zero to 10 scale) for proportions. In addition, stones were rated for symmetry and finish. If the diamond was rated zero for each, it earned a coveted “triple zero.”

The AGS cut grade was an instant success, especially with cutters who specialized in “hearts and arrows” diamonds that tended to be cut to Tolkowsky proportions (34.5 crown angle and 40.75 pavilion angle).

Unfortunately, many dealers resented the AGS cut grading system. They accused the group of being unfairly partial to one set of proportions and ignoring others which could produce equally beautiful diamonds. One leading critic of the AGS cut grading system was GIA, which was engaged in monumental research toward its own system.

After publishing scientific papers on the three recognized components of diamond beauty—brilliance, fire, and sparkle—GIA performed 70,000 visual comparisons of diamonds cut to different standards with members of the trade and public. This database of actual consumer preferences became the basis of its cut grading system introduced in January 2006. In the meantime, AGS, to its credit, responded to critics of its exclusionary standard and widened its definition of exemplary proportions.

Diamond ring
Image 1 - Diamond ring from the “Rose” collection by Dalumi.
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.