Many tourmaline crystal have radial fractures (perpendicular to the c axis) that limit the yield from a crystal. Even if they are not noticeable in the finished gemstone because of the of its rich tone value, they should be removed, because they can in danger the physical integrity of the gemstone. Sometimes they have been known to propagate ahead of the cutting plane and prevent the completion of the stone. Other times if you grind fast enough you can catch it. The exercise is not really fun.
The posted emerald cut has a light residual mark from a radial fracture in the middle of the gemstone. It is not visible face up, but would pose a threat to the stone during setting. The rest of the features of this stone are classic closed ended, green, emerald cut tourmaline. It weighs 2.21 carats.