|This is a bicolor piece of quartz that has a traditional facet cut on the top, but is finished with a series of concave facets on the back. Each side of the center line has concave facets running parallel to those on the opposite side. The net effect is a herringbone like pattern coming through the top of the stone.
The crossing effect is created by each set of side bars being reflected in the opposite side. The stone was cut in Hong Kong by the SM Gem Group. See closeups below for more detail. It is likely (although not positive) that the stone is synthetic quartz due to the precise and very straight color change line.