Ratnapura alluvial chrysoberyl cat's-eye: parallel hollow tube chatoyancy physics?

Chatoyancy in Ceylon chrysoberyl (Cymophane / Vaidurya) is created by dense clouds of microscopic, hollow tubular channels or fine rutile silk needles oriented parallel to the c-crystallographic axis. When the gem is cut as an oval cabochon with a high dome and its flat base ground parallel to the inclusions, a sharp, silvery-white line of reflected light focuses across the center. When illuminated with a single directional light source positioned at 45 degrees to the line, the stone displays the classic "milk-and-honey" effect: the half facing the light appears honey-yellow, while the opposite side displays milky-white.