What Hearts & Arrows Patterning Does for a Diamond
All ideal cut round diamonds will have robust light return. The benefit of Hearts and Arrows patterning reveals itself in differing lighting conditions and surroundings, particularly in softer conditions.
Bright, direct light makes any diamond perform well, particularly the spotlighting you see in common jewelry stores. These overhead spotlights are designed to maximize brilliance and fire in order to sell any diamond. The balance of what you see does depend on the cut, but since so much light is entering and exiting the stone the 'fine-tuning' of what you see does not impact your eye as much as the sheer 'volume' of the light return does.
A cloudy day or an office with fluorescent lights is an example of diffuse light. This is one of the least desirable conditions for any diamond and is typically an environment in which you see almost no dispersion (fire). Well-cut diamonds return white light well so the diamond may appear very bright, but the amount of fire you will see is muted, which logically mutes scintillation. In diffused lighting Hearts & Arrows diamonds perform better than other diamonds due to better, uniform contrast patterns. The precision of cut and symmetrical areas of contrast allow the viewer to see more fire through a normal range of tilt than in less uniform cuts.
Where H&A diamonds really stand out is in soft light such as candlelight, gas lantern, near a lone computer monitor in a dark room, or surrounded by many small distant light sources. When all of the diamond's tiny mirrors are precisely aligned and the minor facet construction is well-balanced these diamonds maximize the return of all available light they are taking in. True Hearts & Arrows diamonds are those from which you see broad colorful flashes from someone's finger across a candlelit restaurant. They dance and sparkle and perform their best in romantic conditions. It’s a logical result of all of the facets, the mirrors inside the diamond, working in harmony.
Another benefit of Hearts & Arrows diamonds with proper major proportions is improved face-up color. Diamonds are color-graded in the face-down position, viewed from the side. Superior light return maximizes brilliance, fire and scintillation and makes the diamond appear more colorless.