Poorly polished facets may reduce the intensity of light reflected from, or refracted into and out of, a diamond. Polish is graded the same way as symmetry: Ideal, Excellent, Very Good, Good, Fair or Poor on a GIA report. Ideally a diamond has many pleasing flashes spread across the surface of the stone, with few dull dead patches. Under pin point or spot lights fire also adds to scintillation. Black and white sparkles of scintillation show well in flood lit or office lighting environments where fire can be totally absent. Scintillation is the intense sparkles in a diamond as it moves. Less light return makes it easier to see fiery flashes that might otherwise be swamped by bright white sparkles this is one reason is why old cut diamonds and some fancy cuts appear to have a lot of fire. But this combination also produces less light return. There are several factors that greatly influence the amount of fire a diamond produces such as star facet length, lower girdle facet length, pavilion angle, facet junctions, the angle at which light enters the diamond, and the angle of the light rays as they exit the diamond.ĭiamond experts have known for a long time that steep crown angles and small tables (like 'old cut' diamonds) produce more fire. Fire is also a result of a diamond's symmetry and proportions. You see more fire in darker environments like restaurants that have just a few point light sources or just a flickering candle. Consider the contrast of a chess board, although it has only 1/2 the light return of a sheet of white paper, it appears brighter, especially when it is moved because it 'scintillates'.įire or dispersed light appears as flashes of rainbow colors. To be brilliant, a diamond needs more than just brightness. Diamonds that are too deep or very shallow do this -they have areas that act like a mirror back to the viewer they return less light and so they have less brightness. But light that enters and leaves in the face up direction is wasted because your head blocks the lights. ![]() ![]() If light from above leaks out the back of a diamond, naturally it has less brightness. Bright diamonds return lots of light from the surroundings back up through the crown to a 'face up' observer. Brilliance is an essential attribute of a beautiful diamond and has 2 components brightness and contrast.
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