Pavilion
pa·vil·ion | pə-ˈvil-yən
noun
The portion of a gemstone located below the girdle
The pavilion of a diamond is the portion that exists below the girdle - the lower half of the cut stone. The pavilion is not typically seen as much as the rest of the diamond because it is the portion that is set into the ring. The facets of the pavilion slope between the girdle and the culet at the point of the diamond. It is still equally important, however, because the way the facets are cut will determine how the light enters and bounces through the diamond. This directly impacts the fire and brilliance of a diamond. When the pavilion isn’t deep enough, light can pass directly through the stone. When not shallow enough, light will reflect too low and not come out at the correct location above the girdle where the stone is most visible.