The bottom-most facets on the diamond (the main pavilion facets) draw their light from the highest angles. When a Hearts & Arrows diamond is photographed from directly overhead, these areas will go dark if the camera blocks, or obstructs, the light source. This is known as obstruction. The dark areas are, literally, a reflection of the viewer or camera lens in the crown of the diamond.
Properly designed diamonds maximize positive contrast patterns which create on/off reflections and scintillation (sparkle) in the diamond with even the slightest motion. The precision of the contrast patterns can be seen in certain static views such as our magnified diamond images, ideal scope and ASET images. In real life, because there is almost always some motion either of the diamond or the eye of the viewer, the contrast patterns are not readily visible. For more information see our page about light performance imaging.
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