Brightness
The appearance, or extent, of internal and external reflections of "white" light seen in a polished diamond when it is viewed face-up.

Craftsmanship
A description of the care that went into the crafting of a polished diamond, as seen in the finish (polish and symmetry) of the diamond.

Design
Decisions made during the fashioning process that determine a diamond's physical shape, as seen in a diamond's proportions, weight ratio, and durability.

Durability
The characteristic of a polished diamond that accounts for the risk of damage inherent in its proportions (i.e., the risk of chipping in diamonds with extremely thin girdles).

Face-up appearance
The sum appearance (brightness, fire, and scintillation) of a polished diamond when it is viewed in the table-up position. This appearance includes what is seen when the diamond is "rocked" or "tilted."

Fire
The appearance, or extent, of spots of light dispersed into spectral colors seen in a polished diamond when it is viewed face-up.

Metric
A calculated numerical result obtained through computer modeling; for the GIA diamond cut research project, metrics were calculated for brightness and fire for both hypothetical and actual diamonds.

Overall cut appearance and quality
A description of a polished diamond that includes the face-up appearance, design, and craftsmanship of that diamond.

Scintillation
1. Sparkle: The appearance, or extent, of spots of light seen in a polished diamond when it is viewed face-up that flash as the diamond, observer, or light source moves.

2. Pattern: The relative size, arrangement, and contrast of bright and dark areas that result from the internal and external reflections seen in a polished diamond when it is viewed face-up while that diamond is still or moving.

Weight Ratio
A description of a diamond's overall weight in relation to its diameter.

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