Half-Carat Aquamarine, .50ct, in a baguette cut 6mm x 4mm, with the corners of the gemstone cut, the so-called “emerald” cut. The name for this type of cut of square-shaped and baguette gemstones comes from these cuts in Emerald often having their corners shaved to  make it easier, less problematic for the gemstone setter. For the gemstone setter to properly fix the gemstone in place requires considerable, if judicious, force, and when pressure is applied to Emerald, a gemstone characteristically much-included, it can fracture, especially on corners; thus the “emerald” cut, the corners shaved, allowing the setter more assurance of forcing the metal into place without causing damage.
Aquamarine, though belonging to the same Crystal family as Emerald, namely the Beryl Crystal family, and though sharing many of the same crystal structures, is much less vulnerable than Emerald to the aforementioned danger of fracture, simply because fine Aquamarine gemstone without much in the way of inclusions is considerably less rare than the same in Emerald; in natural Emerald it is almost impossible to find a specimen not hugely included.
The “emerald” cut is, however, attractive in its own right, and is often enough used for its own sake.