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

When cut to the correct proportions with facets properly shaped and aligned, a diamond is the ultimate light performance machine. Depending on the lighting environment in which the stone is viewed, the light will take three forms: brilliance, fire, and scintillation.


When people think of diamond brilliance, they tend to think of the overall brightness and intensity of white light reflected from the crown (top portion) of a diamond. The greater the amount of white light return, the greater the brilliance.

But brightness is only part of the story. A bright diamond with a glaring, white snowball-like appearance is lacking aspects of true diamond brilliance.

If you look at a diamond, or a good photo of one, you will notice that there is an element of sharp, highly defined contrast to its brilliance. A highly brilliant diamond exhibits what looks like a mosaic pattern of light-dark areas across the entire upper part of the stone. These bright-dark areas are evenly distributed over the diamond. There are no rings of light dropout near the center, no constantly dark edges around the girdle. There is what research gemologist Michael Cowing calls “bright, high contrast, edge-to-edge radiance.” Only well-cut diamonds have such radiance.


Have you ever noticed emissions of rainbow colors of light from a diamond? These can appear as large flashes or pinpoints of spectrum color, both the result of white light dispersion.

This colored light is called fire and is most commonly seen when stones are looked at under multiple, high-contrast light sources. For instance, look at a diamond when illuminated with light fractured by passage through tree leaves or a trellis. This is an ideal setting to observe fire because light-fracturing produces the high-contrast lighting necessary to observe fire. “If there is no contrast in the illumination, there will be no fire,” Cowing notes.

Unfortunately, when seated at a jewelry counter, you are most likely to view a diamond under strong overhead spotlights accompanied by bright fluorescent lights and a bright white ceiling—the kind of high-intensity illumination that emphasizes brilliance and sparkle. “There’s fire, but it’s drowned out by the diamond’s intense brilliance and sparkle,” says Cowing.

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.