A new type of Russian hydrothermal synthetic emerald is produced by seeded growth in steel autoclaves without noble-metal inserts; the seed slices have been cut parallel to a face of the second-order hexagonal dipyramid s(1121). This seed orientation avoids the easily recognizable growth pattern seen in earlier Russian production. However, characteristic growth planes of a different nature—that is, parallel to s and forming a 45° angle with the optic axis—are present in the new material.
