As is adzed diamond for CAD?
You can specify any angle(cut) fo crystal(brilliant):
1.modify main scetch
2.modify is everyone polygon from scetch
3.modify is angle of rotation(it is curve to the intersection of two surfaces)
4. basic line segments should be tangential to the cone( basic is body of revolution)
Answered with a tutorial: https://grabcad.com/tutorials/as-is-adzed-diamond-for-cad