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

No wonder fire is the most misunderstood, and endangered, aspect of diamond beauty. In the jewelry stores of the 19th and early 20th century, where high-contrast gas and carbon arc lamps were still the most common lighting sources, fire was much more noticed and appreciated. Hence diamonds were cut for the best balance between fire and brilliance. Now, thanks to breakthroughs in high-performance cutting, consumers have the option of asking for stones which display strong fire in the fire-friendly lighting just described.


Brilliance and fire are light performance characteristics observable in stationary diamonds or images of them. However, with movement comes a dynamic aspect of diamond beauty. As they are moved or tilted, diamonds exhibit mixed white and colored sparkles called scintillation.

Don’t confuse the tiny colored pinfire of scintillation with the large flashes of fire present in the finest of diamond cuts. Many modern round brilliant diamonds are cut for maximum sparkle which results in an unintended reduction of desirable large flash brilliance and fire. Alas, maximum sparkle can douse much of a diamond’s fire, especially in stones cut with dozens of extra scintillation-producing facets. Why? Extra facets split light rays into smaller and smaller reflections. While these reflections give the diamond added animation, they deprive it of the large colored flashes which purists say is true fire. (see image 8)


For more than a century, it was assumed that diamonds cut to certain proportions would optimally balance brilliance and fire. Believe it or not, these proportions were discovered by one of America’s first diamond cutters, Bostonian Henry Morse, some time between 1860 and 1870. By the end of the 19th century, Morse’s assumptions and methods had been embraced by most of America’s premier cutting firms. Indeed, his version of the 57 facet round brilliant was known as “the scientific cut”—a tribute to its superior brilliance and fire.

In the early 20th century, American apostles of Morse’s ideas re-christened the “scientific cut” the “ideal cut.” The new name became most associated with Belgian cutter Marcel Tolkowsky whose 1919 treatise on diamond cutting, “Diamond Design,” made recommendations very similar to Morse’s 50 years earlier. Tolkowsky himself never used the term “ideal,” preferring the more modest phrase “high-class brilliant.”

However, Tolkowsky’s math addressed only 17 of the round brilliant diamond’s 57 facets: the table, the eight crown mains, and the eight pavilion mains. These are the first facets of a round brilliant diamond to be cut during a preliminary stage known as blocking. The remaining 40 facets (the 16 lower halves or girdle facets, the 16 crown halves or upper girdle facets, and the eight star facets) are cut during the final stage known as brillianteering. For decades, the diamond world assumed that stones cut to Tolkowsky’s proportions would give maximum brilliance, fire, and sparkle. While buttressed by observation, it remained an assumption.

Around 1984, several Japanese firms introduced diamond “hearts and arrows” viewers that showed the total light behavior of all 57 facets. For the first time, people could see evidence that their diamond had been cut to proper proportions, as well as the impressive impact of superb symmetry and exact facet alignments on diamond performance. These devices validated Tolkowsky’s theoretical proportions and pushed the art of diamond cutting into the realm of science.

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.